West Nile Virus vaccine

ABSTRACT

The invention provides for immunogenic compositions against West Nile Virus. The immunogenic compositions, in alternate embodiments, also include other equine pathogens. The West Nile Virus composition of the present invention advantageously provides for protection against North American Dominant West Nile Virus strains or isolates.

BACKGROUND

West Nile Virus (“WNV”) is in the family Flavivirade. Infection is usually contracted through a mosquito vector transferred through the insect's bite. West Nile infects all types of animals and birds across the globe. This virus was first discovered in the North American region in 1999 with the first diagnosis occurring in Canadian horses. Presently, West Nile Virus has become endemic in the United States affecting birds, humans, and animals of all types. In 2002, over 14,700 confirmed cases of West Nile Virus were reported in 43 states.

The spread of WNV has been influenced by several factors. Since the mosquito is the vector for the virus and perpetuates WNV, the ecological conditions conducive to growth and development of mosquito populations have had an impact of the spread of the WNV. There are several tactics that have been utilized to control populations of mosquitoes in an effort to prevent the spread of WNV. These tactics include the use of pesticides, repellants, physical barriers preventing contact between mosquitoes and animals, eliminating environments that perpetuate breeding of mosquitoes, and the use of immunizations. Typical signs of WNV include various symptoms affecting the central nervous system. Symptoms of encephalitis are often seen and include viremia, histopathologic lesions of the central nervous system, anorexia, depression, fever, weakness, abnormal gait, paralysis of hind limbs, impaired vision, ataxia, aimless wandering, convulsions, inability to swallow, coma, and death.

A few vaccines directed towards WNV have been introduced which are undesirable for various reasons. For example, one vaccine was produced from a canarypox-vectored West Nile Virus. Another set of vaccines were produced from a recombinant chimeric protein of West Nile Virus, wherein the chimeric protein vaccine was designed by fusing a modified version of bacterial flagellin (STF2 Delta) to the EIII domain of the WNV envelope protein. Another vaccine included an inactivated early North American West Nile strain that required a metabolizable oil as an adjuvant. Finally, a live, attenuated chimeric vaccine was produced from an infectious clone of yellow fever 17D virus in which the pre-membrane and envelope proteins have been replaced by the corresponding genes of WN(4).

There are several problems inherent in vaccines described above. Vaccines containing live viral organisms have the risk of infecting an animal with the virus through vaccination leading to sickness and even death. Chimeric protein vaccines, recombinantly expressed vaccines, and some subunit vaccines have the problem of limited immunological activity and effect related to the number of proteins included in the vaccine composition. The efficacy of these types of vaccines is usually limited and the risk of infection by the virus or reversion to wild type virus is prevalent. In addition, some of the adjuvants utilized in common vaccines are comprised of metabolizable oils which are removed relatively rapidly from the body and limit the duration during which the immune system of the vaccinated animal may respond to the immunogenically active composition. Other adjuvants can cause allergic reactions and unfavorable effects in the vaccinated animals. Additionally, these vaccines do not include antigens for stimulating immunity to other pathogens besides WNV, so they fail to protect animals against several diseases with both convenience and safety. Also, all previous vaccines were derived from an early isolate of WNV that is no longer present in the environment, and hence, can no longer infect animals and cause disease.

Accordingly, what is needed in the art is a vaccine that is safe for administration to animals of all ages, including pregnant animals, that includes adjuvants suitable for aiding the immunogenic effect and duration of the vaccine, and that is prepared from contemporary or dominant isolates of WNV that remain present in the natural environment and cause disease against which such vaccines would afford protection. What is further needed is a vaccine that reduces the incidence and/or severity of up to and including the elimination or prevention of clinical signs associated with the disease or infection by West Nile Virus. Additionally what is needed is a vaccine against West Nile virus, which includes West Nile Virus antigens in combination with antigens from other equine pathogens, thereby providing further protection by reducing the incidence of or severity of clinical signs of disease from both West Nile Virus and the other pathogen(s).

SUMMARY OF INVENTION

The present invention overcomes the problems inherent in the prior art and provides a distinct advance in the state of the art. More particularly, the present invention provides for a vaccine or immunogenic composition comprising an immunogenically active antigenic component comprised of one or more strains or isolates of West Nile Virus. In some preferred embodiments, the composition further comprises an adjuvant, preferably a carbomer, and a pharmaceutically acceptable carrier. Preferably, the West Nile Virus antigen is killed or inactivated. This composition induces an immunogenic response in animals susceptible to contraction of West Nile Virus and provides for a safe vaccine for animals of any age.

The present invention additionally provides for a vaccine composition, which is immunogenically active, and which overcomes the limitations of those previously described. The present invention provides an inactivated vaccine thereby providing unique safety for the vaccinated animals, including pregnant females. Additionally, the immunogenic composition of the present invention overcomes interference from passively acquired maternal immunity and stimulates active immunity in vaccinated animals. Advantageously, the present invention provides a broad and effective immunogenically active composition containing many or all relevant antigenic components and proteins of pathogenic WNV. The immunogenic composition of the present invention is unique in that it includes antigens of contemporary isolates or epidemiologically dominant isolates of WNV in the composition, providing protective immunogenic responses by reducing the incidence of and/or severity of clinical signs of WNV infection up to and including immunity against the most prevalent isolates seen in animals, including horses, today. In a preferred embodiment, those contemporary isolates of WNV include those isolates that are part of the North American West Nile Virus isolates or North American Dominant West Nile Virus isolates For purposes of the present invention, WN02 is a representative example of a WNV strain that can be referred to as a North American Dominant West Nile Virus strain or isolate. Specifically, North American Dominant strains and isolates are those having at least 1 nucleotide change resulting in an amino acid change from the WN99 isolates. Strain NY99 (GenBank accession no. AF196835) serves as a reference strain for determining if a strain or isolate is North American Dominant. In addition, these strains or isolates may have one or more silent amino acid changes. In a preferred embodiment, the nucleotide change results in an amino acid change in an envelope protein of the strain or isolate and, more preferably, the nucleotide change results in an amino acid change from valine to alanine. Preferably, this amino acid change is associated with a greater ability to replicate in the intermediate host, namely, the mosquito. More preferably, North American Dominant strains include either (and preferably both) a U to C mutation and a C to U mutation at positions 1442 and 2466 (in comparison to a North American strain, e.g. NY 99 and SEQ ID NO.23), respectively. Still more preferably, North American Dominant strains or isolates further include a mutation in the nucleotide sequence encoding the E protein and the C to U mutation at position 9352 in the sequence encoding the NS5 protein (again in comparison to a North American strain, e.g. NY 99 and SEQ ID NO. 23). These preferred mutations are shown in Example 10 and in Phylogenetic Analysis of North American West Nile Virus Isolates, 2001-2004: Evidence For the Emergence of a Dominant Genotype, C. Todd Davis, et. al, Virology 342, p. 252-265 (2005), the teaching and content of which is hereby incorporated by reference herein.

The present invention also provides for a method of making the immunogenic composition of the present invention. The method generally comprises the steps of combining a West Nile Virus antigen and an excipient or pharmaceutically or veterinary acceptable carrier. A preferred embodiment further comprises the step of adding one or more additional equine antigens. In another embodiment, the method further comprises the step of adding a suitable adjuvant to the composition.

In one preferred embodiment, the present invention includes WNV antigens and a non-metabolizable oil adjuvant, preferably mineral oil, to extend the duration during which the immune system of the vaccinated animal may respond to the immunogenically active composition. The non-metabolizable oil is understood to be an oil that, when administered with an antigen, does not metabolize in the body after administration. A preferred non-metabolizable oil is mineral oil. In other preferred forms, both a carbomer adjuvant and non-metabolizable oil (preferably mineral oil) are present in addition to the WNV antigens. The adjuvant(s) can be used in any of the compositions described herein.

In an additional embodiment, the composition of the present invention contains WNV antigens, preferably an inactivated or killed WNV from a North American dominant strain, and essentially no oil or oil-based adjuvants. In such an embodiment, other adjuvants, preferably carbomer, can be included.

In another embodiment, a vaccine composition comprised of WNV antigens in combination with other antigens from equine microbial pathogens is provided in order to confer a broad scope of protection to the animal. In such embodiments, the WNV antigens are in any form as described above.

In one preferred embodiment, the present invention provides a vaccine composition comprising WNV antigens as described above in combination with one or more immunologically effective amounts of antigenic components selected from the group consisting of Venezuelan Equine Encephalomyelitis (VEE), Eastern Equine Encephalomyelitis (EEE), Western Equine Encephalomyelitis (WEE), Tetanus toxoid (T), Equine herpes viruses (EHV) including types 1 and 4, Equine influenza viruses (EIV), and combinations thereof, along with a pharmaceutically acceptable carrier. Preferably such embodiments will include an adjuvant, preferably carbomer, and a pharmaceutically acceptable carrier. Additionally, a non-metabolizable oil, preferably mineral oil, may be present, however, such an oil is not required.

Preferred embodiments also include WNV antigens, as described above, in combination with: Eastern Equine Encephalomyelitis; Western Equine Encephalomyelitis; Venezuelan Equine Encephalomyelitis; Tetanus Toxoid; Eastern Equine Encephalomyelitis and Western Equine Encephalomyelitis; Eastern Equine Encephalomyelitis and Venezuelan Equine Encephalomyelitis; Eastern Equine Encephalomyelitis and Tetanus Toxoid; Eastern Equine Encephalomyelitis, Western Equine Encephalomyelitis, and Venezuelan Equine Encephalomyelitis; Eastern Equine Encephalomyelitis, Western Equine Encephalomyelitis, and Tetanus Toxoid; Eastern Equine Encephalomyelitis, Western Equine Encephalomyelitis, Venezuelan Equine Encephalomyelitis and Tetanus Toxoid; Western Equine Encephalomyelitis and Venezuelan Equine Encephalomyelitis; Western Equine Encephalomyelitis and Tetanus Toxoid; Western Equine Encephalomyelitis, Venezuelan Equine Encephalomyelitis, and Tetanus Toxoid; Venezuelan Equine Encephalomyelitis and Tetanus Toxoid; and Eastern Equine Encephalomyelitis, Venezuelan Equine Encephalomyelitis and Tetanus Toxoid. The most preferred combination of these specified combinations includes WNV antigens in combination with antigens or antigenic components of Eastern Equine Encephalomyelitis, Western Equine Encephalomyelitis, Venezuelan Equine Encephalomyelitis, and Tetanus Toxoid. In each such specified combination, an adjuvant or combination of adjuvants can be used, with carbomer, and even more preferably carbopol, being particularly preferred. In the most preferred forms of the combination of WNV and Eastern Equine Encephalomyelitis, Western Equine Encephalomyelitis, Venezuelan Equine Encephalomyelitis and Tetanus Toxoid, no oil (metabolizable or non-metabolizable) is present. The NJO strain of Eastern Equine Encephalomyelitis, the Fleming strain of Western Equine Encephalomyelitis strain, and the TC-83 strain of Venezuelan Equine Encephalomyelitis strain are all representative strains of these vaccine components.

Further preferred embodiments of the present invention can be made using each of the specified combination vaccines listed above and adding in antigens from Equine Herpesvirus, preferably type 1, type 4, (EHV1 and/or EHV4) or combinations thereof.

Still further variations of each of the specified combination vaccines listed above, including those that include EHV1 and/or EHV4 can be made by adding in antigens from Equine influenza virus (EIV). Preferred embodiments incorporating Equine influenza virus include: West Nile Virus, at least one strain of Equine Influenza Virus, and Tetanus Toxoid; West Nile Virus, at least one strain of Equine Influenza Virus, Tetanus Toxoid, and Eastern Equine Encephalomyelitis; West Nile Virus, at least one strain of Equine Influenza Virus, Tetanus Toxoid, Eastern Equine Encephalomyelitis, and Western Equine Encephalomyelitis; West Nile Virus, at least one strain of Equine Influenza Virus, Tetanus Toxoid, Eastern Equine Encephalomyelitis, Western Equine Encephalomyelitis; and Venezuelan Equine Encephalomyelitis; West Nile Virus, at least one strain of Equine Influenza Virus, and Eastern Equine Encephalomyelitis; West Nile Virus, at least one strain of Equine Influenza Virus, and Western Equine Encephalomyelitis; West Nile Virus, at least one strain of Equine Influenza Virus, and Venezuelan Equine Encephalomyelitis; West Nile Virus, at least one strain of Equine Influenza Virus, Eastern Equine Encephalomyelitis, and Western Equine Encephalomyelitis; West Nile Virus, at least one strain of Equine Influenza Virus, Eastern Equine Encephalomyelitis, and Venezuelan Equine Encephalomyelitis; West Nile Virus, at least one strain of Equine Influenza Virus, Western Equine Encephalomyelitis, and Venezuelan Equine Encephalomyelitis; West Nile Virus, at least one strain of Equine Influenza Virus, Western Equine Encephalomyelitis, and tetanus toxoid; West Nile Virus, at least one strain of Equine Influenza Virus, Venezuelan Equine Encephalomyelitis, and tetanus toxoid; West Nile Virus, at least one strain of Equine Influenza Virus, Venezuelan Equine Encephalomyelitis, Western Equine Encephalomyelitis, and tetanus toxoid; and West Nile Virus, at least one strain of Equine Influenza Virus, Venezuelan Equine Encephalomyelitis, Eastern Equine Encephalomyelitis, and tetanus toxoid. In each specified embodiment any one or more strains or isolates of Equine Influenza may be present. Preferred strains of Equine Influenza virus include Influenza A/equine-2/Ohio/03, Influenza A/equine-2/New Market/2/93, Influenza A/equine-2/Kentucky/95, and combinations thereof. In all of the combinations listed above, it is preferred to use at least two strains of Equine Influenza and still more preferred to use at least 3 strains of Equine Influenza. Preferred embodiments incorporating Equine Herpes Virus include: West Nile Virus, at least one strain of Equine Influenza Virus, Tetanus Toxoid, and Equine Herpes Virus; West Nile Virus, at least one strain of Equine Influenza Virus, Tetanus Toxoid, Eastern Equine Encephalomyelitis, and Equine Herpes Virus; West Nile Virus, at least one strain of Equine Influenza Virus, Tetanus Toxoid, Eastern Equine Encephalomyelitis, Western Equine Encephalomyelitis, and Equine Herpes Virus; West Nile Virus, at least one strain of Equine Influenza Virus, Tetanus Toxoid, Eastern Equine Encephalomyelitis, Western Equine Encephalomyelitis; Venezuelan Equine Encephalomyelitis, and Equine Herpes Virus; West Nile Virus, at least one strain of Equine Influenza Virus, and Eastern Equine Encephalomyelitis; West Nile Virus, at least one strain of Equine Influenza Virus, Western Equine Encephalomyelitis and Equine Herpes Virus; West Nile Virus, at least one strain of Equine Influenza Virus, Venezuelan Equine Encephalomyelitis, and Equine Herpes Virus; West Nile Virus, at least one strain of Equine Influenza Virus, Eastern Equine Encephalomyelitis, Western Equine Encephalomyelitis, and Equine Herpes Virus; West Nile Virus, at least one strain of Equine Influenza Virus, Eastern Equine Encephalomyelitis, Venezuelan Equine Encephalomyelitis, and Equine Herpes Virus; West Nile Virus, at least one strain of Equine Influenza Virus, Western Equine Encephalomyelitis, Venezuelan Equine Encephalomyelitis, and Equine Herpes Virus; West Nile Virus, at least one strain of Equine Influenza Virus, Western Equine Encephalomyelitis, Tetanus Toxoid, and Equine Herpes Virus; West Nile Virus, at least one strain of Equine Influenza Virus, Venezuelan Equine Encephalomyelitis, tetanus toxoid, and Equine Herpes Virus; West Nile Virus, at least one strain of Equine Influenza Virus, Venezuelan Equine Encephalomyelitis, Western Equine Encephalomyelitis, Tetanus Toxoid, and Equine Herpes Virus; and West Nile Virus, at least one strain of Equine Influenza Virus, Venezuelan Equine Encephalomyelitis, Eastern Equine Encephalomyelitis, Tetanus Toxoid, and Equine Herpes Virus. In all of the combinations listed above, it is preferred to use at least two strains of Equine Influenza and still more preferred to use at least 3 strains of Equine Influenza. Additionally, in all combinations above, the “at least one” strain of Equine Herpesvirus is preferred to be selected from the group consisting of EHV-1 and EHV-4. In some preferred forms, both strains, EHV-1 and EHV-4, will be included in the immunogenic composition. In other preferred forms, just EHV-1 will be included. The WNV component of the combination will preferably be an inactivated or killed North American dominant strain as described herein.

The vaccine composition can be administered in any immunogenically effective dose. In a preferred embodiment, the vaccine composition is administered as a single dose. Preferably, the dose has a total volume between about 0.5 ml and 2.5 ml, more preferably between about 0.6 ml and 2.0 ml, even more preferably between about 0.7 ml and 1.75 ml, still more preferably between about 0.8 ml and 1.5 ml, even more preferably between about 0.9 ml and 1.25 ml, with a single 1.0 ml dose being the most preferred.

In another embodiment, the vaccine is administered with a first dose being administered prior to the administration of a second (booster) dose. Preferably, the second dose is administered at least 15 days after the first dose. More preferably, the second dose is administered between 15 and 28 days after the first dose. Even more preferably, the second dose is administered at least 17 days after the first dose. Still more preferably, the second dose is administered between 17 and 25 days after the first dose. Even more preferably, the second dose is administered at least 19 days after the first dose. Still more preferably, the second dose is administered between 19 and 23 days after the first dose. Most preferably the second dose is administered at least 21 days after the first dose. In a preferred embodiment, both the first and second doses of the vaccine are in the same amount. Preferably, each dose is in the preferred amounts specified above, with a dose of 1 ml for the first and second dose being most preferred. In addition to the first and second dose regimen, an alternate embodiment comprises further subsequent doses. For example, a third, fourth, or fifth dose could be administered in these embodiments. Preferably, subsequent third, fourth, and fifth dose regimens are administered in the same amount as the first dose, with the time frame between the doses being consistent with the timing between the first and second doses mentioned above.

In an additional preferred embodiment, in each dose of the composition of the present invention, the WNV antigen comprises at least 10^(2.0) TCID₅₀/dose. More preferably, the WNV antigen comprises between about 10^(2.0) TCID₅₀/dose to 10^(10.0) TCID₅₀/dose. Still more preferably, the WNV antigen comprises at least 10^(2.5) TCID₅₀/dose. Even more preferably, the WNV antigen comprises between about 10^(2.5) TCID₅₀/dose to about 10^(9.5) TCID₅₀/dose. Still more preferably, the WNV antigen comprises at least 10^(3.0) TCID₅₀/dose. Even more preferably, the WNV antigen comprises between about 10^(3.0) TCID₅₀/dose to about 10^(9.0) TCID₅₀/dose. Still more preferably, the WNV antigen comprises at least 10^(3.5) TCID₅₀/dose. Even more preferably, the WNV antigen comprises between about 10^(3.5) TCID₅₀/dose to about 10^(9.0) TCID₅₀/dose. Most preferably, the WNV antigen comprises between 10^(7.0) TCID₅₀/dose and 10^(9.0) TCID₅₀/dose. The TCID₅₀ values of an inactivated WNV vaccine or any other inactivated vaccine refer in general to the antigen content in the final vaccine that however is equivalent to the antigen content calculated for the vaccine composition prior to the inactivation of its antigen. Preferably, the immunogenic composition of the present invention stimulates serum neutralizing antibodies to WNV at a titer of 1:4 or higher when determined in a commercial available detection assay or using the procedures known to those of skill in the art with a representative example provided herein. In a preferred embodiment, in each dose of an embodiment of the present invention that comprises additional equine antigen, the amount of Eastern Equine Encephalomyelitis or Venezuelan Equine Encephalomyelitis in any dose is preferably at least 10^(5.5) TCID₅₀/dose. Even more preferably, the dose is between about 10^(5.5) TCID₅₀/dose and 10^(9.5) TCID₅₀/dose. Still more preferably, the dose is at least 10^(6.0) TCID₅₀/dose. Still more preferably, the dose is between about 10^(6.0) TCID₅₀/dose and 10^(9.0) TCID₅₀/dose. Even more preferably, the dose is at least 10^(6.5) TCID₅₀/dose. Still more preferably, the dose is between about 10^(6.5) TCID₅₀/dose and 10^(9.5) TCID₅₀/dose. Even more preferably, the dose is at least 10^(7.0) TCID₅₀/dose. Most preferably, the dose is between 10^(6.7) TCID₅₀ and 10^(9.2) TCID₅₀/dose.

Preferably, the Western Equine Encephalomyelitis antigen, when present in the composition of the present invention, is in an amount of at least 10^(6.2) PFU/ml. Even more preferably, the amount is between 10^(6.2) PFU/ml and 10^(10.2) PFU/ml. Still more preferably, the amount is at least 10^(6.7) PFU/ml. Even more preferably, the amount is between 10^(6.5) PFU/ml and 10^(9.7) PFU/ml. Still more preferably, the amount is at least 10^(7.2) PFU/ml. Even more preferably, the amount is between about 10^(7.2) PFU/ml and 10^(9.2) PFU/ml. Still more preferably, the amount is at least 10^(7.7) PFU/ml with at between 10^(6.5) PFU/dose and 10^(9.0) PFU/ml being the most preferred.

In another preferred embodiment, the amount of tetanus toxoid, if present in the composition of the present invention, is in an amount of at least 3 CPU, more preferably, between about 3 CPU and 20 CPU, still more preferably, at least 4 CPU, and most preferably, at least 5 CPU but not more than 20 CPU.

In an alternate embodiment, where one or more strains of Equine Influenza Virus is present, the amount of Equine Influenza present in the composition is in an amount of at least 10^(5.0) TCID₅₀/mL. More preferably, the Equine Influenza is in an amount of between about 10^(5.0) TCID₅₀/mL to 10^(9.0) TCID₅₀/mL, and, more preferably, at least 10^(6.0) TCID₅₀/mL. Still more preferably, the amount is between about 10^(6.0) TCID₅₀/mL to 10^(8.0) TCID₅₀/mL and, more preferably, the amount is at least 10^(6.5) TCID₅₀/mL. Still more preferably, the amount is between about 10^(6.5) TCID₅₀/mL to 10^(7.0) TCID₅₀/mL, with the most preferred amount being between about 10^(6.7) TCID₅₀/mL to 10^(7.0).

In an embodiment that comprises Equine Herpes Virus, the amount of Equine Herpes Virus in each dose is at least 10^(6.0) TCID₅₀/mL. More preferably, Equine Herpes Virus is present in the composition in an amount of between 10^(6.0) TCID₅₀/mL to 10^(9.5) TCID₅₀/mL and, more preferably, in an amount of about 10^(7.0) TCID₅₀/mL. Still more preferably, Equine Herpes Virus is present in an amount between 10^(7.5) TCID₅₀/mL to 10^(9.0) TCID₅₀/mL and, more preferably, in an amount of about 10^(8.0) TCID₅₀/mL. Still more preferably, Equine Herpes Virus is present in an amount of between 10^(8.0) TCID₅₀/mL to 10^(9.0) TCID₅₀/mL and, most preferably, in an amount of about 10^(8.50) TCID₅₀/mL.

In yet another preferred embodiment, a vaccine composition comprising the chronologically contemporary and epidemiologically prevalent strains of WNV is provided. Such a composition will generally improve the efficacy of the composition. Preferably, such a prevalent strain is isolated from the tissues of a horse. Such a source is a preferred source of WNV for preparing vaccine seed virus for an immunological composition for a species for which a comprehensively safe and effective WNV vaccine is particularly needed, namely, the horse. Further, the present invention discloses a vaccine composition comprising an inactivated low passage strain of WNV from the tissues of a horse, thereby overcoming the limitations of previous vaccines with the inappropriate limited repertoire of protein antigens found in either high passage attenuated vaccines, subunit vaccines, or other compositions produced by recombinant technology that express less than the full complement of proteins. This inactivated low passage WNV strain, isolated from horse tissues, overcomes deficiencies inherent in previous vaccines and provides a broad number of immunogenic proteins of most relevance by virtue of being produced from a highly virulent equine strain of low passage, thereby comprising a uniquely and comprehensively effective, yet safe, immunogenic composition not previously available for vaccination of the horse. Additionally, preferred chronologically contemporary and epidemiologically prevalent strains of WNV are North American dominant WNV strains, as defined herein.

The present invention provides for a broader scope of protection than traditional immunogenic or vaccine compositions, as the present invention provides protection against a broad range of isolates of a particular antigen. The challenge model used to evaluate the efficacy of the composition of the present invention utilized a heterologous challenge strain, evidencing the composition's ability to provide protection to isolates and strains outside of the particular strain or isolate used to vaccinate the animal. This is a unique feature of the present invention.

The present invention additionally provides for a method of reduction of the incidence and/or severity of clinical signs associated with West Nile Virus infection in an animal, preferably a horse, when compared to wild type infection. Such methods generally comprise the step of administering a vaccine composition comprising a killed or inactivated isolate of West Nile virus, preferably a North American dominant WNV strain, and a pharmaceutically acceptable carrier. In some preferred embodiments of the present application, an adjuvant is added to the composition, and in other preferred forms, no adjuvant is provided. In an alternate preferred embodiment, the method comprises administering a vaccine composition comprising one or more killed or inactivated isolate(s) of West Nile virus in combination with immunologically effective amounts of antigenic components from other equine pathogens. Preferably those isolates are selected from the group consisting of Eastern Equine Encephalomyelitis antigen, Western Equine Encephalomyelitis antigen, Venezuelan Equine Encephalomyelitis antigen, tetanus toxoid, and combinations thereof, and more preferably being those combinations described above. In another preferred embodiment, the vaccine of the present invention is combined with a suitable adjuvant, diluent, or pharmaceutically acceptable carrier.

The present invention provides for reduction of the incidence and/or severity of clinical symptoms associated with West Nile Virus infection in a herd, when compared to wild type infection. Preferably, the severity and/or incidence of clinical symptoms in animals receiving the immunogenic composition of the present invention are reduced at least 10% in comparison to animals not receiving such an administration when both groups (animals receiving and animals not receiving the composition) are challenged with or exposed to wild type infection by WNV. More preferably, the incidence or severity is reduced at least 20%, even more preferably, at least 30%, still more preferably, at least 40%, even more preferably, at least 50%, still more preferably, at least 60%, even more preferably, at least 70%, still more preferably, at least 80%, even more preferably, at least 90%, still more preferably, at least 95%, and most preferably, at least 100%, wherein the animals receiving the composition of the present invention exhibit no clinical symptoms. Preferably, the WNV strain is a North American dominant strain of WNV. Advantageously, the present invention also provides protection from heterologous strains (relative to the strain used in the composition) of pathogens.

The present invention further provides a method of stimulating serum neutralizing or serum hemagglutination antibodies to a pathogen selected from the group consisting of WNV, WEE, VEE, EEE, EHV, EIV, and combinations thereof by administering a composition in accordance with the present invention described herein. Preferably the compositions of the present invention stimulate serum neutralizing antibodies to WNV at a titer of 1:4 or higher, thereby preventing or reducing WNV viremia.

The immunogenic composition of the present invention provides an extended duration of immunity against all antigens present in the vaccine. Preferably, the duration of immunity against West Nile is at least 1 month, more preferably, the duration of immunity is at least 2 months, still more preferably, the duration of immunity is at least 3 months, even more preferably, the duration of immunity is at least 4-24 months, still more preferably, the duration of immunity is at least 6-24 months, even more preferably, the duration of immunity is at least 7-24 months, still more preferably, the duration of immunity is at least 8-24 months, even more preferably, the duration of immunity is at least 9-24 months, still more preferably, the duration of immunity is at least 10-24 months, and most preferably, the duration of immunity is at least 12-24 months.

Preferably, the duration of immunity against EIV is at least 1 month, more preferably, the duration of immunity is at least 2 months, still more preferably, the duration of immunity is at least 3 months, even more preferably, the duration of immunity is at least 4-24 months, still more preferably, the duration of immunity is at least 6-24 months, even more preferably, the duration of immunity is at least 7-24 months, still more preferably, the duration of immunity is at least 8-24 months, even more preferably, the duration of immunity is at least 9-24 months, still more preferably, the duration of immunity is at least 10-24 months, and most preferably, the duration of immunity is at least 12-24 months.

Preferably, the duration of immunity against EHV is at least 1 month, more preferably, the duration of immunity is at least 2 months, still more preferably, the duration of immunity is at least 3 months, even more preferably, the duration of immunity is at least 4-24 months, still more preferably, the duration of immunity is at least 6-24 months, even more preferably, the duration of immunity is at least 7-24 months, still more preferably, the duration of immunity is at least 8-24 months, even more preferably, the duration of immunity is at least 9-24 months, still more preferably, the duration of immunity is at least 10-24 months, and most preferably, the duration of immunity is at least 12-24 months.

Preferably, the duration of immunity against Western Equine Encephalomyelitis is at least 1 month, more preferably, the duration of immunity is at least 2 months, still more preferably, the duration of immunity is at least 3 months, even more preferably, the duration of immunity is at least 4-24 months, still more preferably, the duration of immunity is at least 6-24 months, even more preferably, the duration of immunity is at least 7-24 months, still more preferably, the duration of immunity is at least 8-24 months, even more preferably, the duration of immunity is at least 9-24 months, still more preferably, the duration of immunity is at least 10-24 months, and most preferably, the duration of immunity is at least 12-24 months.

Preferably, the duration of immunity against Eastern Equine Encephalomyelitis is at least 1 month, more preferably, the duration of immunity is at least 2 months, still more preferably, the duration of immunity is at least 3 months, even more preferably, the duration of immunity is at least 4-24 months, still more preferably, the duration of immunity is at least 6-24 months, even more preferably, the duration of immunity is at least 7-24 months, still more preferably, the duration of immunity is at least 8-24 months, even more preferably, the duration of immunity is at least 9-24 months, still more preferably, the duration of immunity is at least 10-24 months, and most preferably, the duration of immunity is at least 12-24 months.

Preferably, the duration of immunity against Venezuelan Equine Encephalomyelitis is at least 1 month, more preferably, the duration of immunity is at least 2 months, still more preferably, the duration of immunity is at least 3 months, even more preferably, the duration of immunity is at least 4-24 months, still more preferably, the duration of immunity is at least 6-24 months, even more preferably, the duration of immunity is at least 7-24 months, still more preferably, the duration of immunity is at least 8-24 months, even more preferably, the duration of immunity is at least 9-24 months, still more preferably, the duration of immunity is at least 10-24 months, and most preferably, the duration of immunity is at least 12-24 months.

Preferably, the duration of immunity against Tetanus Toxoid is at least 1 month, more preferably, the duration of immunity is at least 2 months, still more preferably, the duration of immunity is at least 3 months, even more preferably, the duration of immunity is at least 4-24 months, still more preferably, the duration of immunity is at least 6-24 months, even more preferably, the duration of immunity is at least 7-24 months, still more preferably, the duration of immunity is at least 8-24 months, even more preferably, the duration of immunity is at least 9-24 months, still more preferably, the duration of immunity is at least 10-24 months, and most preferably, the duration of immunity is at least 12-24 months.

Preferably, the duration of immunity of at least 12 months further relates to any combination of antigens forming the immunogenic composition of the present invention.

In another preferred embodiment comprising EIV and/or EHV antigen, as described above, the immunogenic composition ameliorates shedding of infectious EIV or EHV to prevent spread of the virus to other susceptible animals.

In yet another preferred embodiment, compositions in accordance with the present invention described herein overcome interference from passively acquired maternal immunity and stimulates active immunity and a reduction in the incidence of or severity of clinical signs of EIV infection in vaccinated animals against EIV.

In another preferred embodiment of the present invention, an immunogenic composition comprising VEE, WEE, EEE, tetanus, WNV, equine rhinopneumonitis and equine influenza, all as described herein, demonstrates efficacy against VEE, WEE, EEE, tetanus, WNV, equine rhinopneumonitis and equine influenza after administration in accordance with the present invention. Preferably, such a composition will further include an adjuvant, preferably mineral oil and/or a carbomer, and a veterinary acceptable carrier. In preferred forms, the composition will be administered in a single, 1 ml dose.

Each of the immunogenic compositions described herein that include WNV antigen can be administered as described such that they reduce the incidence of or lessen the severity of clinical symptoms associated with West Nile Virus.

Each of the immunogenic compositions described herein that include EIV antigen can be administered as described such that they reduce the incidence of or lessen the severity of clinical symptoms associated with Equine Influenza.

The present invention also provides a method for reducing the incidence of or lessening the severity of clinical symptoms associated with Equine Herpes virus comprising the step of administering any one of the immunogenic compositions described above, that includes an Equine Herpes virus antigen, to an animal.

The present invention also provides a method for reducing the incidence of clinical symptoms associated with West Nile Virus comprising the step of administering any one of the immunogenic compositions that includes West Nile Virus antigen, as described herein, to an animal.

The present invention also provides a method for reducing the incidence of clinical symptoms associated with Equine Influenza Virus comprising the step of administering any one of the immunogenic compositions described above, that includes an Equine Influenza antigen, to an animal.

The present invention further provides a method for reducing the incidence of clinical symptoms associated with Equine Herpes Virus comprising the step of administering any one of the immunogenic compositions described above that includes an Equine Herpes virus antigen, to an animal.

The present invention also provides a method of reducing the incidence of clinical symptoms associated with Equine Influenza Virus comprising the step of administering any one of the immunogenic compositions described above to an animal, wherein the reduction in clinical signs, compared to animals not receiving the immunogenic composition, is at least a 10% reduction in clinical signs.

The present invention provides a method of reducing the incidence of infection in a herd comprising the step of administering any one of the immunogenic compositions described above to an animal.

The present invention provides a method of reducing the incidence of infection in a herd comprising the step of administering any one of the immunogenic compositions described above to an animal, wherein the reduction of incidence of infection, compared to herds not receiving the immunogenic composition, is from about 10%-50% reduction.

The present invention provides a method of reducing the incidence and severity of clinical symptoms of EHV in a herd, wherein the clinical symptoms are selected from the group consisting of respiratory disease, abortion, reproductive complications, neurological disease, central nervous system disease, and combinations thereof.

The present invention provides a method for reducing the incidence of or lessening the severity of clinical symptoms associated with Equine Herpes Virus comprising the step of administering any one of the immunogenic compositions described above, that includes an Equine Herpes Virus antigen, to an animal.

The present invention provides a method for reducing the severity of or lessening the severity of clinical symptoms associated with Equine Influenza in a herd, comprising the step of administering any one of the immunogenic compositions described above, that includes an Equine Influenza antigen, to an animal.

The present invention provides a method for reducing the incidence of or lessening the severity of clinical symptoms associated with West Nile Virus in a herd, comprising the step of administering any one of the immunogenic compositions described above, that includes a West Nile Virus antigen, to an animal.

The present invention provides a method for reducing the incidence of or lessening the severity of clinical symptoms associated with Eastern Equine Encephalomyelitis in a herd, comprising the step of administering any one of the immunogenic compositions described above that includes an Eastern Equine Encephalomyelitis antigen to an animal.

The present invention further provides a method for reducing the incidence of or lessening the severity of clinical symptoms associated with Western Equine Encephalomyelitis in a herd, comprising the step of administering any one of the immunogenic compositions described above, that includes an Western Equine Encephalomyelitis antigen, to an animal.

The present invention further provides a method for reducing the incidence of or lessening the severity of clinical symptoms associated with Venezuelan Equine Encephalomyelitis in a herd, comprising the step of administering any one of the immunogenic compositions described above, that includes a Venezuelan Equine Encephalomyelitis antigen, to an animal.

The present invention also provides a method of making any one of the immunogenic composition of the present invention as described above and herein, comprising the steps of combining a West Nile Virus antigen with a suitable excipient or pharmaceutical carrier. In preferred forms, this method further comprises the step of adding one or more equine antigens. A preferred group of equine antigens are selected from the group consisting of Western Equine Encephalomyelitis, Eastern Equine Encephalomyelitis, Venezuelan Equine Encephalomyelitis, Tetanus Toxoid, EHV, EIV, and combinations thereof. In some preferred forms, the methods described herein can further comprise a filtration step, wherein the final product is in a purified form.

“Adjuvants” as used herein, can include aluminum hydroxide and aluminum phosphate, saponins e.g., Quil A, QS-21 (Cambridge Biotech Inc., Cambridge Mass.), GPI-0100 (Galenica Pharmaceuticals, Inc., Birmingham, Ala.), non-metabolizable oil, mineral and/or plant/vegetable and/or animal oils, polymers, carbomers, surfactants, natural organic compounds, plant extracts, carbohydrates, cholesterol, lipids, water-in-oil emulsion, oil-in-water emulsion, water-in-oil-in-water emulsion. The emulsion can be based in particular on light liquid paraffin oil (European Pharmacopeia type); isoprenoid oil such as squalane or squalene; oil resulting from the oligomerization of alkenes, in particular of isobutene or decene; esters of acids or of alcohols containing a linear alkyl group, more particularly plant oils, ethyl oleate, propylene glycol di-(caprylate/caprate), glyceryl tri-(caprylate/caprate) or propylene glycol dioleate; esters of branched fatty acids or alcohols, in particular isostearic acid esters. The oil is used in combination with emulsifiers to form the emulsion. The emulsifiers are preferably nonionic surfactants, in particular esters of sorbitan, of mannide (e.g. anhydromannitol oleate), of glycol, of polyglycerol, of propylene glycol and of oleic, isostearic, ricinoleic or hydroxystearic acid, which are optionally ethoxylated, and polyoxypropylene-polyoxyethylene copolymer blocks, in particular the Pluronic products, especially L121. See Hunter et al., The Theory and Practical Application of Adjuvants (Ed. Stewart-Tull, D. E. S.). John Wiley and Sons, NY, pp 51-94 (1995) and Todd et al., Vaccine 15:564-570 (1997). In a preferred embodiment the adjuvant is at a concentration of about 0.01 to 50%, preferably at a concentration of about 2% to 30%, more preferably at a concentration of about 5% to 25%, still more preferably at a concentration of about 7% to 22%, and most preferably at a concentration of 10% to 20% by volume of the final product. Of the possible adjuvants used in combination with the present invention, it is preferred to not use a metabolizable oil. In a preferred embodiment, the adjuvant is at least a non-metabolizable oil, preferably mineral oil. In an alternate preferred embodiment, the vaccine composition contains essentially no oil-based adjuvants. In a most preferred embodiment the vaccine composition contains both a non-metabolizable oil, preferably mineral oil, and carbomer as adjuvants.

In addition, the immunogenic and vaccine compositions of the present invention can include one or more veterinary-acceptable carriers. As used herein, “a veterinary-acceptable carrier” includes any and all solvents, dispersion media, coatings, adjuvants, stabilizing agents, diluents, preservatives, excipients, antibacterial and antifungal agents, antimicrobic agents, isotonic agents, adsorption delaying agents, and the like. In some preferred embodiments, and especially those that include lyophilized immunogenic compositions, stabilizing agents for use in the present invention include stabilizers for lyophilization or freeze-drying.

“Diluents” can include water, saline, dextrose, ethanol, glycerol, and the like. Isotonic agents can include sodium chloride, dextrose, mannitol, sorbitol, and lactose, among others. Stabilizers include albumin and alkali salts of ethylendiamintetracetic acid, among others.

In a preferred embodiment, the immunogenic composition of the present invention is prepared comprising a preservative and a stabilizer; and, more preferably, the immunogenic composition of the present invention is prepared comprising gentamycin, EDTA, Glycerol, and combinations thereof.

An “immunogenic or immunological composition” refers to a composition of matter that comprises at least one antigen, which elicits an immunological response in the host of a cellular and/or antibody-mediated immune response to the composition or vaccine of interest. Usually, an “immunological response” includes but is not limited to one or more of the following effects: the production or activation of antibodies, B cells, helper T cells, suppressor T cells, and/or cytotoxic T cells and/or gamma-delta T cells, directed specifically to an antigen or antigens included in the composition or vaccine of interest. Preferably, the host will display either a therapeutic or protective immunological response such that resistance to new infection will be enhanced and/or the clinical severity of the disease reduced. Such protection will be demonstrated by either a reduction or lack of clinical signs normally displayed by an infected host, a quicker recovery time and/or a lowered duration or bacterial titer in the tissues or body fluids or excretions of the infected host.

The term “in need of such administration” or “in need of such administration treatment”, as used herein means that the administration/treatment is associated with the boosting or improvement in health or any other positive medicinal effect on health of the animals which receive the immunogenic composition in accordance with the present invention.

The term “West Nile Virus” antigen means, but is not limited to the components of the WNV virion that are immunogenic when present in an animal, and most particularly protein components, such as envelope and non-structural proteins, of the WNV that provoke humoral or cellular immune responses when present in an animal. Such antigens can include DNA, protein subunits, modified live virus, and killed or inactivated virus. In preferred forms of the invention, the WNV antigen or antigens comprise inactivated or killed, and even more preferably, North American dominant, WNV strains.

The term “North American West Nile Virus (strains)” refers to, but is not limited to any West Nile Virus strain or isolate that has ever been discovered on the North American continent. Preferably, a North American West Nile Virus strain has a sequence identity to the NY99 strain (GenBank accession no. AF196835 or NCBI reference sequence NC_(—)00942.1 (SEQ ID No. 23) of at least 97%, even more preferably, at least 98%, still more preferably, at least 98.5%, more preferably, at least 99%, even more preferably, at least 99.2%, and, most preferably of at least 99.4%.

“Sequence Identity” as it is known in the art refers to a relationship between two or more polypeptide sequences or two or more polynucleotide sequences, namely a reference sequence and a given sequence to be compared with the reference sequence. Sequence identity is determined by comparing the given sequence to the reference sequence after the sequences have been optimally aligned to produce the highest degree of sequence similarity, as determined by the match between strings of such sequences. Upon such alignment, sequence identity is ascertained on a position-by-position basis, e.g., the sequences are “identical” at a particular position if at that position, the nucleotides or amino acid residues are identical. The total number of such position identities is then divided by the total number of nucleotides or residues in the reference sequence to give % sequence identity. Sequence identity can be readily calculated by known methods, including but not limited to, those described in Computational Molecular Biology, Lesk, A. N., ed., Oxford University Press, New York (1988), Biocomputing: Informatics and Genome Projects, Smith, D. W., ed., Academic Press, New York (1993); Computer Analysis of Sequence Data, Part I, Griffin, A. M., and Griffin, H. G., eds., Humana Press, New Jersey (1994); Sequence Analysis in Molecular Biology, von Heinge, G., Academic Press (1987); Sequence Analysis Primer, Gribskov, M. and Devereux, J., eds., M. Stockton Press, New York (1991); and Carillo, H., and Lipman, D., SIAM J. Applied Math., 48: 1073 (1988), the teachings of which are incorporated herein by reference. Preferred methods to determine the sequence identity are designed to give the largest match between the sequences tested. Methods to determine sequence identity are codified in publicly available computer programs which determine sequence identity between given sequences. Examples of such programs include, but are not limited to, the GCG program package (Devereux, J., et al., Nucleic Acids Research, 12(1):387 (1984)), BLASTP, BLASTN and FASTA (Altschul, S. F. et al., J. Molec. Biol., 215:403-410 (1990). The BLASTX program is publicly available from NCBI and other sources (BLAST Manual, Altschul, S. et al., NCVI NLM NIH Bethesda, Md. 20894, Altschul, S. F. et al., J. Molec. Biol., 215:403-410 (1990), the teachings of which are incorporated herein by reference). These programs optimally align sequences using default gap weights in order to produce the highest level of sequence identity between the given and reference sequences. As an illustration, by a polynucleotide having a nucleotide sequence having at least, for example, 85%, preferably 90%, even more preferably 95% “sequence identity” to a reference nucleotide sequence, it is intended that the nucleotide sequence of the given polynucleotide is identical to the reference sequence except that the given polynucleotide sequence may include up to 15, preferably up to 10, even more preferably up to 5 point mutations per each 100 nucleotides of the reference nucleotide sequence. In other words, in a polynucleotide having a nucleotide sequence having at least 85%, preferably 90%, even more preferably 95% identity relative to the reference nucleotide sequence, up to 15%, preferably 10%, even more preferably 5% of the nucleotides in the reference sequence may be deleted or substituted with another nucleotide, or a number of nucleotides up to 15%, preferably 10%, even more preferably 5% of the total nucleotides in the reference sequence may be inserted into the reference sequence. These mutations of the reference sequence may occur at the 5′ or 3′ terminal positions of the reference nucleotide sequence or anywhere between those terminal positions, interspersed either individually among nucleotides in the reference sequence or in one or more contiguous groups within the reference sequence. Analogously, by a polypeptide having a given amino acid sequence having at least, for example, 85%, preferably 90%, even more preferably 95% sequence identity to a reference amino acid sequence, it is intended that the given amino acid sequence of the polypeptide is identical to the reference sequence except that the given polypeptide sequence may include up to 15, preferably up to 10, even more preferably up to 5 amino acid alterations per each 100 amino acids of the reference amino acid sequence. In other words, to obtain a given polypeptide sequence having at least 85%, preferably 90%, even more preferably 95% sequence identity with a reference amino acid sequence, up to 15%, preferably up to 10%, even more preferably up to 5% of the amino acid residues in the reference sequence may be deleted or substituted with another amino acid, or a number of amino acids up to 15%, preferably up to 10%, even more preferably up to 5% of the total number of amino acid residues in the reference sequence may be inserted into the reference sequence. These alterations of the reference sequence may occur at the amino or the carboxy terminal positions of the reference amino acid sequence or anywhere between those terminal positions, interspersed either individually among residues in the reference sequence or in the one or more contiguous groups within the reference sequence. Preferably, residue positions which are not identical differ by conservative amino acid substitutions. However, conservative substitutions are not included as a match when determining sequence identity.

The term “North American Dominant West Nile Virus” strains and isolates refers to those strains or isolates defined as such in Phylogenetic Analysis of North American West Nile Virus Isolates, 2001-2004: Evidence For the Emergence of a Dominant Genotype, C. Todd Davis, et. al, Virology 342, p. 252-265 (2005), the teaching and content of which is hereby incorporated by reference herein. As noted therein, North American Dominant WNV strains or isolates have at least 1 nucleotide change resulting in an amino acid change from the WN99 isolates. Strain NY99 (GenBank accession no. AF196835), an example of which is provided in SEQ ID. NO. 23, serves as a reference strain for determining if a strain or isolate is North American Dominant. In a preferred embodiment, the nucleotide change results in an amino acid change in an envelope protein of the strain or isolate and, more preferably, the nucleotide change results in an amino acid change from valine to alanine at position 159 in the critical envelope protein or “E159”. Preferably, this amino acid change is associated with a greater ability to replicate in the intermediate host, namely, the mosquito. In addition, these strains or isolates may have one or more silent amino acid changes. Preferably, North American Dominant strains also include either (and preferably both) a U to C mutation and a C to U mutation at positions 1442 and 2466 (in comparison to a North American strain, e.g. NY 99 and SEQ ID NO.23), respectively. Still more preferably, North American Dominant strains or isolates further include a mutation in the nucleotide sequence encoding the E protein and the C to U mutation at position 9352 in the sequence encoding the NS5 protein (again in comparison to a North American strain, e.g. NY 99 and SEQ ID NO. 23). These preferred mutations are shown in detail for specific regions in Example 10 and FIGS. 10-17. Representative North American Dominant WNV strains are listed in this application. Additionally, for purposes of the present invention North American Dominant and WN02 are used interchangeably.

For purposes of the present invention, Horse Origin 2005 strain North American Equine E159, E159 (Horse Origin), NAEE159, United States Department of Agriculture Isolate 405330 (USDA 2005) Horse Origin, and E159 strain are used interchangeably. For purposes of the present invention, Donkey Origin 2004 strain, United States Department of Agricultures Isolate 292206 (USDA 2004) Donkey Origin, E159 (Donkey Origin), and North American Donkey E159 (NADE159) are used interchangeably. E159 indicates that the amino acid change in the envelope protein from valine to alanine occurs at position 159, as described above.

West Nile Virus strains or isolates, for purposes of the present invention, are not limited to horse and equine West Nile Virus strains but encompass, while not being limited to, those West Nile Virus strains of bird origin, donkey origin, pig origin, human origin, mammal origin, and equine origin.

For purposes of the present invention the terms “strain” and “isolate” have the same meaning and are used interchangeably.

As used herein, “a pharmaceutically” or “veterinary acceptable carrier” or “pharmaceutical carrier” includes any and all solvents, growth media, dispersion media, coatings, adjuvants, stabilizing agents, diluents, preservatives, antibacterial and antifungal agents, isotonic agents, adsorption delaying agents, and the like.

An “immunogenic or immunological composition” refers to a composition of matter that comprises at least one antigen which elicits an immunological response in the host of a cellular and/or antibody-mediated immune response to the composition or vaccine of interest. Usually, an “immunological response” includes but is not limited to one or more of the following effects: the production or activation of antibodies, B cells, helper T cells, suppressor T cells, and/or cytotoxic T cells and/or gamma-delta T cells, and/or virus neutralizing antibodies directed specifically to an antigen or antigens included in the composition or vaccine of interest. Preferably, the host will display either a therapeutic or protective immunological response such that resistance to new infection will be enhanced and/or the clinical severity of the disease reduced. Such protection will be demonstrated by either a reduction or lack of clinical signs normally displayed by an infected host, a quicker recovery time and/or a lowered duration of clinical disease or higher viral antibody titer in the tissues or body fluids or excretions of the infected host, or lessened viremia in the blood, or lessened gross or histopathological lesions due to infection.

In addition, the immunogenic and vaccine compositions of the present invention can include one or more veterinary-acceptable carriers. As used herein, “a veterinary-acceptable carrier” includes any and all solvents, dispersion media, cell culture media and cell culture constituents, coatings, adjuvants, stabilizing agents, diluents, preservatives, antibacterial and antifungal agents, isotonic agents, adsorption delaying agents, and the like. “Diluents” can include water, saline, buffered saline, dextrose, ethanol, glycerol, and the like. Isotonic agents can include sodium chloride, dextrose, mannitol, sorbitol, and lactose, among others. Stabilizers include albumin and alkali salts of ethylendiamintetracetic acid, among others.

“Clinical signs” of West Nile Virus, for purposes of this invention, include, but are not limited to, symptoms or lesions associated with encephalitis, viremia, anorexia, depression, fever, weakness, abnormal gait, paralysis of hind limbs, impaired vision, ataxia, aimless wandering, convulsions, inability to swallow, coma, posterior weakness, paralysis, poor coordination, depression and related behavior, tremors, convulsions, paddling of the limbs, neurological problems, swelling of the central nervous system, death, and combinations thereof. The clinical signs exhibited by an infected animal vary depending on the severity of infection

“Clinical Signs” of Equine Herpes virus, for purposes of this invention include, but are not limited to, abortion, neurological deficiencies, respiratory disease, reproductive system deficiencies and failure, and symptoms relating to the central nervous system. Additionally, clinical symptoms of EHV 1 include, but are not limited to, the phenomenon of foals infected with EHV1, exhibiting respiratory complications, passing the virus to the older members of the herd who then exhibit reproductive deficiencies, including abortion, and neurological deficiencies, normally exhibited in the central nervous system.

“Clinical Signs” of Eastern Equine Encephalomyelitis, Western Equine Encephalomyelitis, and Venezuelan Equine Encephalomyelitis, for purposes of the present invention are those symptoms normally known to be associated with encephalomyelitis, including, but are not limited to fever, nervous signs such as sensitivity to sound, periods of excitement, and restlessness, brain lesions, drowsiness, drooping ears, circling, abnormal gait, paralysis, loss of appetite, depression, head pressing, lack of coordination, long-term disability, brain damage, death, and combinations thereof. “Safety” as used herein, refers to the absence of adverse consequences in the vaccinated animal following vaccination, including but not limited to, potential reversion of vaccine virus to virulence and clinically significant side effects, such as persistent systemic illness or unacceptable inflammation at the site of vaccine administration.

“Reduction of the incidence and/or severity of clinical signs” or “reduction in the incidence and/or severity of clinical symptoms”, as referred to herein, means reducing the number of infected animals in a group, reducing or eliminating the number of animals exhibiting clinical signs of infection, or reducing the severity of any clinical signs that are present in the animals, in comparison to wild-type infection. For example, in the experiments herein, such clinical signs included viremia, fever, antibody response, and histopathology. Preferably, these are reduced in animals receiving the composition of the present invention by at least 10% in comparison to animals not receiving the vaccination which may become infected. More preferably, clinical signs are reduced in animals receiving the composition of the present invention by at least 20%, more preferably by at least 30%, even more preferably by at least 40%, and even more preferably by at least 50%.

“Duration of Immunity,” as used herein, refers to the minimum number of days during which an animal produces an immunogenic response such that the animal will be relatively immune from contracting a virus and/or benefit from reduction of incidence and/or severity of clinical signs, as described herein.

The terms “strain” and “isolate”, when used herein, are meant to be used interchangeably.

The terms “vaccine” and “immunogenic composition”, when used herein, are meant to be used interchangeably.

Any West Nile Virus strain(s) or isolate(s) can be used in accordance with the present invention. In a preferred embodiment, the isolate is selected from one or more of the following: New York (Northeastern North American) Isolate (WN-NY 99), Horse Origin, 1999, New York (Northeastern North American) Isolate (WN-NY 99), Crow Origin, 1999, United States Department of Agricultures Isolate 292206 (USDA 2004), Donkey Origin, United States Department of Agriculture Isolate 405330 (USDA 2005), Horse Origin, North American Isolate (WN-Texas-2002/2003), Southeast Texas Coastal Isolate 2002, Mexico (Tabasco) Isolate 2003, and combinations thereof, and in a more preferred embodiment the isolate is selected from one or more of the following: United States Department of Agricultures Isolate 292206 (USDA 2004), Donkey Origin, United States Department of Agriculture Isolate 405330 (USDA 2005), Horse Origin, North American Isolate (WN-Texas-2002/2003), Southeast Texas Coastal Isolate 2002, Mexico (Tabasco) Isolate 2003, and combinations thereof. In a most preferred embodiment, the isolate is United States Department of Agriculture Isolate 405330 (USDA 2005), Horse Origin singularly or in combination with one or more isolates as listed above. In an additionally preferred embodiment, those isolates which are part of the North American West Nile Virus isolates are included. In yet another preferred embodiment North American Dominant West Nile Virus isolates are included. In addition to those listed above, specific isolates include, but are not limited to, WN02 and isolates which have at least 1, preferably at least 2, and even more preferably at least 3 nucleotide changes resulting in at least one amino acid change from the WN NY99 isolates, and most preferred are strains with the amino acid change from valine to alanine at position 159 of the envelope protein. Most preferred North American Dominant strains include, but are not limited to: NY2002Nassau, NY2002Clinton, NY2002Queens, GA20021, GA20022, TX20021, TX20022, IN2002, NY2003Albany, NY2003Suffolk, NY2003Chatauqua, CO20031, CO20032, TX2003, TX2003Harris4, TX2003Harris6, TX2003Harris7, TX2003Harris10, AZ2004, and TX2004Harris4, and combinations thereof. The strains of West Nile Virus useful in the vaccine or immunogenic composition of the present invention can be any strain or isolate. In a preferred embodiment, the North American Dominant West Nile Virus strain used is either E-159 (Horse Origin) or E-159 (Donkey Origin). A representative strain of such a North American Dominant WNV strain includes the Horse Origin 2005 strain deposited with the ATCC (ATCC Accession No. PTA-9409), located at 10801 University Boulevard, Manassas, Va., 20110-2209, on Aug. 14, 2008, under the provisions of the Budapest Treaty. Equine Influenza strains useful in the vaccine or immunogenic composition of the present invention can be any strain or isolate. Representative strains include Equi-2/Ohio/03, deposited as ATCC Accession No. PTA-9522, Equi-2/Kentucky/95, deposited as ATCC Accession No. PTA-9523, and Equi-2/New Market/2/93, deposited as ATCC Accession No. PTA-9524. Representative strains ATCC Accession Nos. PTA-9522, PTA-9523, and PTA-9524 were each deposited with the ATCC at 10801 University Boulevard, Manassas, Va., 20110-2209 on Sep. 23, 2008, under the provisions of the Budapest Treaty.

Equine Herpes Virus (“EHV”) strains useful in the vaccine or immunogenic composition of the present invention can be any strain or isolate. Representative strains include EHV Subtype 1, deposited as ATCC Accession No. PTA-9525, and EHV Subtype 4, deposited as ATCC Accession No. PTA-9526. Representative strains ATCC Accession Nos. PTA-9525 and PTA-9526 were each deposited with the ATCC at 10801 University Boulevard, Manassas, Va., 20110-2209 on Sep. 23, 2008, under the provisions of the Budapest Treaty.

Western Equine Encephalomyelitis strains useful in the vaccine or immunogenic composition of the present invention can be any strain or isolate. A representative strain includes the Fleming Strain, deposited with the ATCC (ATCC Accession No. PTA-9410), located at 10801 University Boulevard, Manassas, Va., 20110-2209, on Aug. 14, 2008, under the provisions of the Budapest Treaty.

Venezuelan Equine Encephalomyelitis strains useful in the vaccine or immunogenic composition of the present invention can be any strain or isolate. A representative strain includes the TC-83 strain, deposited with the ATCC (ATCC Accession No. PTA-9411), located at 10801 University Boulevard, Manassas, Va., 20110-2209, on Aug. 14, 2008, under the provisions of the Budapest Treaty.

Eastern Equine Encephalomyelitis strains useful in the vaccine or immunogenic composition of the present invention can be any strain or isolate. A representative strain includes the NJO strain, deposited with the ATCC (ATCC Accession No. PTA-9412), located at 10801 University Boulevard, Manassas, Va., 20110-2209, on Aug. 14, 2008, under the provisions of the Budapest Treaty.

Tetanus toxoid strains useful in the vaccine or immunogenic composition of the present invention can be any strain or isolate. A representative strain is that taken from a master seed of Clostridium tetani from The Massachusetts Department of Public Health Institute of Laboratories in Boston, Mass.

The vaccine of the present invention is safe for administration in WNV susceptible species, particularly equidae, at any age and at any stage of reproduction, including pregnant females. In a preferred embodiment, the present invention is safe for administration to foals 12 months of age or older, more preferably, it is safe for administration to foals 10 months of age or older, more preferably, it is safe for administration to foals 8 months or older, more preferably, it is safe for administration to foals 6 months of age or older, more preferably, is safe for administration to foals 4 months of age or older, more preferably, it is safe for administration to foals 2 months of age or older, more preferably, it is safe for administration to foals 1 month of age or older, even more preferably, it is safe for administration to foals between 1 day and 1 month of age, and, most preferably, it is safe for administration to foals 1 day of age or older.

The composition of the present invention can be administered in any conventional manner. Examples of administration methods include any that afford access by cells of the immune system to the immunogenic composition including oral, transdermal/intradermal, intravenous, subcutaneous, intramuscular, intraocular, intraperitoneal, intrarectal, intravaginal, intranasal, intragastrical, intratracheal, intrapulmonarial, or any combination thereof. In a preferred embodiment, the vaccine is administered parenterally, preferably intranasally, subcutaneously, or intramuscularly, and in the most preferred embodiment the vaccine is administered intramuscularly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical representation of the Mean Total Clinical Scores;

FIG. 2 is a graphical representation of the Proportion Shedding;

FIG. 3 is a graphical representation of the Nasal Discharge Score;

FIG. 4 is a graphical representation of Proportion Virus Shedding;

FIG. 5 is a graphical representation of Conjunctivitis Score;

FIG. 6 is a graphical representation of Serum Neutralization Titers;

FIG. 7 is a graphical representation of Proportion Positive for EHV-1;

FIG. 8 is a graphical representation of Mean White Blood Cell Count;

FIG. 9 is a graphical representation of Proportion Positive (pyrexic);

FIG. 10 is a nucleotide alignment of the HE region of WNV isolates;

FIG. 11 is a nucleotide alignment of the DE region of WNV isolates;

FIG. 12 is a nucleotide alignment of the D NS5 region of WNV isolates;

FIG. 13 is a nucleotide alignment of the H NS5 region of WNV isolates;

FIG. 14 is a nucleotide alignment of the H WN05 E NS5 region of WNV isolates;

FIG. 15 is a nucleotide alignment of the H WN05 region of WNV isolates;

FIG. 16 is a nucleotide alignment of the NS5 region of WNV isolates; and

FIG. 17 is a nucleotide alignment of the E region of WNV isolates.

DETAILED DESCRIPTION Examples

The following examples are set forth below to illustrate specific embodiments of the present invention. These examples are merely illustrative and are understood not to limit the scope or the underlying principles of the present invention.

Example 1

This example illustrates a preferred vaccine composition in accordance with the present invention.

Materials and Methods

For preparation of working cell stock, the Master Cell Stock (MCS), consisting of the Vero Cell Line known to propagate West Nile Virus, which was tested for purity, identity, and karyology, was thawed and used to inoculate a range of T25 up to T150 cm² vessels or 1050 cm² roller bottles, or bioreactors or other suitable sterile vessels. Thawed cells were suspended in growth medium at a rate of 0.0015 mL to 5.0 L per vessel, depending on vessel volume. Cells were then incubated at 36-38° C. for up to seven days. Cultures planted from frozen stock were re-fed with medium, if needed, within thirty-six hours after planting to remove residual DMSO. Cultures were re-fed with medium, if needed, during the growth period to remove excessive debris, or to stimulate the growth of cultures which have not reached confluence, or to maintain viability of confluent cultures.

Cells were passaged 1-20 times by decanting the spent medium and then by adding 5-500 mL of 0.25% Trypsin-EDTA Solution to each vessel, depending upon vessel volume. The vessels were agitated gently until the cells slough from the surface. The cells were then removed from the vessels by rinsing with growth medium and pooled together. Prior to inoculation, cell growth medium was decanted from Vero Working Cells that are at least 55% confluent. Virus growth medium described was added to each vessel at 0.15 to 0.4 mL per cm² surface area. A Multiplicity of Infection (MOI) of 0.000001-0.0002 was used for infection as determined by performing a cell count of at least two representative vessels. Roller bottle cultures infected were incubated at 36-38° C. for two to five days at 0.1-0.8 rpm.

During the growth period, cultures were checked for typical CPE microscopically and for gross contamination macroscopically. Unsuitable cultures were discarded after sterilization. Cultures may be attenuated using standard techniques or may be used without attenuation.

The microorganisms were then harvested for production purposes. Virus fluids were harvested when CPE reached 85% or greater. Roller bottles were swirled to remove loose cells, and fluids and then pooled into sterile 2-20 L glass, plastic, or PETG bottles, 20 L sterile polypropylene containers or 2-500 L sterile stainless steel tanks containers appropriate for clarification.

Next, the product was prepared. Clarified fluids were inactivated with Formaldehyde Solution, USP, 0.2% by volume, or another effective inactivating agent, transferred to a secondary container, and held at 20-25° C. (room temperature) with agitation for forty-eight hours. A sample of at least 12 mL of the inactivated fluids was taken for inactivation assurance testing (described below) prior to concentration. After inactivation was completed, inactivated lot material was held at 2-7° C. for up to sixty days prior to concentration. A number of suitable adjuvants may be added to the vaccine formulation, most preferably a non-metabolizable oil, preferably mineral oil, and/or a carbomer. Typical processing steps may be employed such as mixing, blending, microfluidization, and emulsification, of the adjuvant and/or the harvested virus antigens with other ingredients.

The product was then standardized. Sufficient volumes of clarified, inactivated, concentrated (optional) lots were combined to provide a calculated titer of at least 10^(4.0) TCID₅₀ per dose of each strain in the final product. Multiple lots may be blended to achieve the titer requirements per dose.

The product was then assembled to final formulation. Based on the desired final serial volume, the amounts of antigenic components, adjuvant, stabilizer and diluent were calculated as follows:

-   -   a. West Nile Virus, Horse Origin 2005 (ATCC No. PTA-9409):         minimum 10^(4.0) TCID₅₀/dose     -   b. Adjuvant: The total adjuvant concentration, preferably a non         metabolizable oil, and more preferably mineral oil and/or a         carbomer, in a serial is at least 10% v/v and is added at time         of serial batching/assembly.     -   c. Diluent: An appropriate volume of phosphate buffered saline         (PBS) is added to bring the final volume to the desired volume.     -   d. Additional Formalin: An appropriate volume of 37% Formalin is         added to maintain an appropriate level.     -   e. Gentamicin Sulfate

The required amounts of adjuvant and PBS were combined in a sterile vessel. The pH of this mixture was adjusted to approximately 4.9-5.1 with 10N NaOH or 5N HCl if necessary. Clarified, killed, concentrated West Nile Virus, as well as Gentamicin, and Formalin were added and the pH adjusted to 6.9 to 7.1. This was mixed at 2-6° C. for at least 8 hours, not to exceed 48 hours.

The vaccine was given by typical hypodermic injection, with booster vaccinations if desired. Most preferably, the initial dose and the booster doses were 1 mL volume administered intramuscularly at 21-day intervals. The vaccination regimen of initial and booster dose was given at the most preferred 1 mL dose volume to horses, other equidae, and other WNV susceptible species to reduce the incidence of and or severity of clinical signs of WNV infection, and preferably to prevent infection by WNV as well as to prevent disease due to West Nile Virus infection for a sustained period following vaccination.

Results and Discussion

The vaccine was given by various appropriate parenteral routes, dose volumes, and dosing regimens to animals of varying immunological status for WNV, including naive and those with passive antibody, and provided for long duration of immunity up to and exceeding at least 2 years following vaccination. The vaccine was safe for administration in WNV susceptible species, particularly equidae, at any age and at any stage of reproduction, including pregnant females.

Example 2

This investigation was carried out to obtain an efficacy evaluation of a vaccine to protect horses from challenge with West Nile Virus (WNV).

Materials and Methods

A total of 30 horses were randomly divided into groups of 15 horses each. A total of 20 horses received 2 doses of vaccine at 21-day intervals and 10 horses were used for control. Each group of horses, Block 1 and Block 2, contained 10 vaccinated horses and 5 control horses. The vaccine was a combination including WNV antigen, specifically an inactivated or killed North American Dominant Strain of WNV, Horse Origin 2005 (ATCC Deposit No. PTA-9409) as well as antigenic components of Venezuelan Equine Encephalomyelitis, TC-83 strain (ATCC Deposit No. PTA-9411) Eastern Equine Encephalomyelitis, NJO strain (ATCC Deposit No. PTA-9412) Western Equine Encephalomyelitis, Fleming strain (ATCC Deposit No. PTA-9410) and Tetanus toxoid formulated approximately as follows:

Eastern Equine Encephalomyelitis 10^(6.7-)10^(9.2) TCID₅₀/mL Western Equine Encephalomyelitis 10^(6.7-)10^(9.2) PFU/mL Venezuelan Equine Encephalomyelitis 10^(6.7)-10^(9.2) TCID₅₀/mL West Nile Virus 10^(7.0)-10^(9.) TCID₅₀/mL Tetanus Toxoid 5-10 CPU/mL Adjuvant 100-200 μl/mL Diluent - DMEM containing q.s. Gentamycin (30 μg/mL of diluent volume) Formaldehyde (0.1% of diluent volume)

All groups were challenged with intrathecal inoculation of 1 ml PBS containing approximately 10⁵ pfu of a heterologous strain of WNV (NY99, 4132, crow isolate). The challenge was conducted under ketamine-xylazine anesthesia.

Horses were monitored for a maximum of 14 days, then humanely euthanized. Those that developed severe disease prior to 14 days were euthanized prematurely.

The following data were collected to assess the effectiveness of the vaccine:

-   -   Basic clinical evaluation     -   Body temperature     -   Assay for viremia     -   Histopathology: two sections of brainstem were evaluated by a         board-certified veterinary pathologist.

Sera collected on appropriate days were evaluated for characterization of serologic responses to challenge.

Results and Discussion

Viremia after challenge and serum neutralization titers were considered the primary outcome variables in this study. The first block of horses that had been vaccinated were 100% protected from viremia after challenge in this study. In comparison, 4 of the 5 control horses demonstrated viremia for 4-5 days post-challenge and 1 of 5 control horses demonstrated viremia for 1 timepoint. In addition, serum neutralization titers of vaccinated horses were statistically significantly higher than those of control horses at each time point examined after vaccination. Furthermore, the data establish that a WNV vaccine that provides a serum neutralization titer of 1:4 or higher is effective in preventing WNV viremia. The serum titers and viremia after challenge for Block 1 is summarized in Table 1 below:

TABLE 1 Serum Titers and Viremia for Block 1 Serum Titer Viremia After Challenge Horse Number Treatment Day of Challenge Highest Titer 1 Control <2 390 2 Vaccinate 12 <5 3 Vaccinate 12 <5 4 Control <2 65 5 Control <2 1475 6 Vaccinate 6 <5 7 Vaccinate 97 <5 8 Vaccinate 10 <5 9 Vaccinate 21 <5 10 Vaccinate 35 <5 11 Vaccinate 10 <5 12 Vaccinate 24 <5 13 Vaccinate 4 <5 14 Control <2 235 15 Control <2 165

Viremia after challenge and serum neutralization titers were also considered the primary outcome variables in the second block of horses in this study. In the second block of horses only one vaccinate group horse displayed any timepoints of viremia throughout the challenge period. That horse had 3 separate timepoints on 3 mornings (not those same evenings) with minimal value readings of 5 (where <5 is negative). All control horses in the study (with the exception of one horse which exited the study prematurely but displayed definitive WNV histopathology and was excluded from evaluation) showed high levels of viremia for 1-8 timepoints after challenge.

Since viremia is a prerequisite before virus can cross the blood-brain barrier to cause WNV encephalitis, viremia is well justified as the primary parameter for evaluation of protection in an experimental study of this type.

This study demonstrated that 2 doses of the experimental combination vaccine administered to foals 4 to 5 months of age reliably and effectively stimulated protective serological serum neutralization titers. In addition the data confirm that post vaccination SN titers as low as 1:4 resulting from vaccination using an effectively batched antigen amount of West Nile Virus in this experimental combination vaccine protected vaccinated horses from viremia, clinical disease, and histopathology after a severe intrathecal challenge with a heterologous strain of West Nile Virus.

Histopathology also was different between the two groups with the likelihood of lesions in vaccinates being 40% less in Block 2 and 100% less in Block 1 than the likelihood of lesions in control animals challenged with virulent West Nile virus.

In addition a Control Group horse became weak on his hind legs on Day 9 post-challenge and got progressively worse until he was no longer able to stand. Histopathology of the pons and medulla from this horse showed severe encephalitis and myelitis consistent with WNV pathology that was more prevalent than signs of disease from any other horse in this study.

Two Block 2 control horses in this study displayed 3 days each of clinical signs relating to infection with West Nile Virus. One other control horse had a single timepoint of weakness due to disease. Another control horse did not display any timepoints of clinical signs, although it had multiple days of viremia. Although several vaccinated Block 2 horses in the study had mild to moderate histopathological changes in tissue as a result of the intrathecal challenge of WNV, only very mild clinical disease (mild head tremors) was noted for one vaccinate on one day of the study as compared to multiple days of clinical disease in 2 control horses and a single day of clinical disease in a third control horse.

The results demonstrated that the vaccine is effective and that an immunogenic reaction is induced in the animals that were administered the vaccine. The effectiveness of the vaccine was evidenced in this example by reduction in WNV viremia, by stimulation of high serum neutralization titers to WNV, and by prevention of WNV related clinical signs and histopathology in the brain and meninges. Because this vaccine is comprised of unique constituents, including a long lasting non-metabolizable adjuvant, it was formulated in a low 1 mL dose volume to provide a high degree of safety as a highly immunogenic low passage whole inactivated virus WNV isolate of recent origin and high epidemiological prevalence, and a WNV isolated from the tissues of an infected horse, it provides more comprehensive safety and effectiveness than other vaccines currently available. Additionally, it has the effect of providing a safe vaccine when administered to animals.

Example 3

This example illustrates the efficacy of the immunogenic composition of the present invention against infection by EHV-4

Materials and Methods

Thirty-seven (37) horses, 4-5 months of age, were used in this study. Horses were randomly assigned to either vaccinate or control groups by random number generator and then vaccinated. Twenty-four (24) horses served as vaccinates and thirteen (13) horses were mock-vaccinated control horses. All horses had low (≦1:14, avg.=1:7) EHV-4 serum neutralization (SN) titers prior to initiation of the study, indicative of horses susceptible to infection. The vaccine used was an experimental vaccine and had the following components:

The final formulated vaccine contains the following ingredients per 1 mL dose:

EHV-1 (PTA-9525) 10^(7.0-9.0) TCID₅₀/mL Influenza A2/Ohio/03 (PTA-9522) 10^(6.0-9.5) TCID₅₀/mL Influenza A2/KY/95 (PTA-9523 10^(6.0-9.5) TCID₅₀/mL Influenza A2/NewMarket/2/93 (PTA-9524) 10^(6.0-9.5) TCID₅₀/mL Tetanus Toxoid 5-10 CPU Eastern Equine Encephalomyelitis, 10^(6.7-9.2) TCID₅₀/mL (ATCC Deposit No. PTA-9412) Western Equine Encephalomyelitis, 10^(6.7-9.2) PFU/mL (ATCC Deposit No. PTA-9410) Venezuelan Equine Encephalomyelitis, 10^(6.7-9.2) TCID₅₀/mL (ATCC Deposit No. PTA-9411) West Nile Virus, Horse Origin 2005 10^(7.0-9.0) TCID₅₀/mL (ATCC Deposit No. PTA-9409) Adjuvant 100-200 μl Glycerol 100-200 μl EDTA 240 mM solution 10-20 μl Diluent - DMEM containing q.s. Gentamicin (30 μg/mL of diluent volume) Formaldehyde (0.1-0.2% of diluent volume)

The Experimental Vaccine was administered intramuscularly in a 1 mL dose volume to each of 24 horses in the vaccinate group. Thirteen horses in the control group received a 1 mL dose of adjuvanted DMEM (Lot 004) containing excipients used in the 9-way vaccine (Gentamicin and formaldehyde) but no antigens. Challenge inoculation of virulent EHV-4 HRA005 strain virus was performed 15 days post-booster vaccination.

Each of the vaccinated and control horses was challenged with an EHV-4 strain of virus (HRA005). The titer of the dilute challenge virus was sufficient to provoke disease due to EHV infection in the non-vaccinated horses.

Sedivet® (romifidine hydrochloride), a sedative and analgesic, was administered intravenously to each horse prior to challenge at a dosage of 50 μg/kg of body weight. Each horse was then challenged with the EHV-4 strain HRA005 virus. The challenge virus was administered intranasally as an aerosol produced by a nebulizer into an Equine AeroMask (Trudell Medical International, Ontario, Canada).

Daily morning rectal temperatures were recorded for each of the 37 vaccinated and control horses on Day of Challenge and for 14 days post challenge by means of a calibrated, electronic thermometer (GSA Electronics) probe. The daily rectal temperatures were recorded in degrees Fahrenheit (° F.).

Complete Blood Cell Counts

Venous blood from each of the 37 vaccinated and control horses was collected daily on the Day of Challenge and for 14 days post-challenge directly into a Vacutainer Disodium EDTA tube for Complete Blood Counts.

Nasal Exudate Evaluation

All nasal exudate observations were made prior to collection of nasopharyngeal swabs. On the Day of Challenge and for 14 days post challenge, the nasal passages and muzzle of each of the 37 vaccinated and control horses were examined and graded using the grading and scoring description listed below.

The scoring grades of 0 through 6 were assigned on the basis of the severity of the disease indicated by each of the following classifications:

TABLE 2 Scores for Clinical Symptoms Score sheet Score Description of symptoms designation 0 Essentially normal indicates the horse was clean and essentially EN free of nasal exudate 1 Slight clear serous discharge that may be frequently observed in C-1 both diseased and normal horses 2 Moderate clear serous discharge is indicative of a definite C-2 increase in volume over that normally observed 3 Copious clear serous discharge that is generally observed only in C-3 diseased horses 1.5 Very slight mucopurulent discharge indicates that mucus was VSM definitely present in small amounts in either one or both nostrils 2 Slightly mucopurulent is a discharge easily observed in one or SM both nostrils 4 Moderately mucopurulent indicates that mucoid discharges were MM present in large quantities in both nostrils 6 Heavy mucopurulent indicates that copious amounts of a mucoid HM discharge filled both nostrils Nasopharyngeal Viral Isolation Methods

On each observation test day each nasal passage of each vaccinated and control was sampled deeply by means of sterile swabs. On collection, each of two swabs were immediately placed in a single tube containing 4 mL of chilled transport medium (Dulbecco's Minimal Essential Medium (DMEM) supplemented with 2% FBS, 2× Pen/Strep, 2× Gentamicin, and 2× Amphotericin B).

For isolation of virus, the tubes were mixed, the swabs aseptically removed, and the medium centrifuged at 1500 rpm for 10 minutes to remove particulates. Medium was filtered through a 0.2μ syringe filter prior to inoculation on tissue culture cells. One mL of the clarified transport medium was used to inoculate a 2 cm² one day old monolayer of ED cells grown in a 24 well tissue culture plate from which the growth medium had been aseptically removed. Following inoculation, the inoculum was allowed to adsorb on the cell monolayer for one hour at 37° C. in a humidified incubator containing a 5% CO₂ atmosphere. After the adsorption period, an additional 1 mL of re-feed medium (DMEM containing 2-5% fetal bovine serum (FBS), 2 mM L-glutamine and 3× Gentamicin and 2× Amphotericin B) was added to each well. Following addition of re-feed media the plates were then incubated at 37° C. in a CO₂ incubator. Each test and control tissue culture well was examined microscopically for 7 days for signs of cytopathic effect (CPE) typical of the EHV-4 challenge virus. Wells that were negative at the end of the 7 day observation period were subcultured onto fresh cells and observed for an additional 7 days.

Serum Neutralization Testing Procedure

A standard microtiter serum neutralization test was employed in this study. All sera were tested in sterile flat bottom microtiter plates using 5 wells per dilution and an 8 well dilution series for each of the 5 test wells. Each of the 5 test wells contained 25 μl of serum dilution mixed with 25 μl of the indicator virus and 150 μl of a freshly planted ED cell suspension containing approximately 5×10⁴ cells. The test indicator virus used was EHV-4 HRA005 Lot 033106 SN Stock Virus. In all tests the indicator virus back titration titers ranged between 68-149 TCID₅₀/25 μl. Serum neutralizing antibody titers are expressed as Reed-Muench ID₅₀ titers.

For performance of the test, two-fold dilutions of each test serum was made in a sterile flat bottom microtiter plate using five replicate wells per test serum and an 8 well dilution series. Dilutions were made with an adjustable volume single or multi-channel pipetting instrument using sterile microtiter tips. The volume of serum added each of 5 wells of the first row was 50 μl. All other wells contained 25 μl of DMEM (no FBS). Following serial dilution down the plate, 25 μl was discarded from the last row. 25 μl of a pre-determined dilution of the indicator virus was added to each test well. Plates were then mixed and incubated for one hour at 37° C. in 5% CO₂. On conclusion of the incubation period, 150 μl of a suspension containing 5×10⁴ ED cells was added to each test and cell control well. The plates were incubated at 37° C. in a CO₂ incubator for 5-7 days, at which time plates were microscopically examined for CPE typical of EHV-4. However, any other commercial available test or any test described in the prior art could be used for this purpose.

Results and Conclusion

Nasal Exudate Evaluation

The vaccination group by day interaction was statistically significant for the nasal discharge scores (P<0.05, Table 1). Statistically significant group effects were seen on Days 6-10 and Day 14 post-challenge (lower nasal scores in the vaccinated group).

When the daily scores were summed over the post-challenge period, horses in the vaccinated group had lower total scores than those in the control group (P<0.05, Table 1). The mitigated fraction was estimated to be 0.824 (95% ASE CI: 0.629, 1.000).

TABLE 3 Nasal Discharge Score Mitigated fraction Control Vaccinate P-value (95% ASE CI) Cumulative nasal 28.9 13.6 <0.0001 0.824 discharge score (0.629, 1.000) Conjunctivitis

The vaccination group by day interaction was statistically significant for the conjunctivitis scores. Statistically significant group effects were seen on Days 6, 7, 9, 10, 13 and 14 post-challenge (lower scores in the vaccinated group on 5 of the 6 days, P<0.05, FIG. 2).

Serological Studies

Titers were log transformed prior to the statistical analysis. The vaccination group by day interaction was statistically significant for SN titers. Statistically significant group effects were seen on Day 0 (pre-vaccination; control group titers>vaccinated group titers), Days 35 (the day of challenge) and 7 and 14 days post-challenge (study days 42 and 49). Horses in the vaccinated group had higher titers on Days 35, 42 and 49 than those in the control group (P<0.05, Table 4).

TABLE 4 Titers Study day Control Vaccinated P-value 0 8.31 5.74 0.0303 21 8.25 6.51 0.1639 35 (day of challenge) 6.12 8.56 0.0495 42 4.57 7.27 0.0069 49 4.87 13.12 <0.0001 White Blood Cell Counts (WBC) and Lymphocyte Counts

The vaccination group by day interaction was statistically significant for WBC and lymphocyte counts. Statistically significant group effects were seen on Days 4-6 (WBC) and Days 4 and 5 (lymphocytes) post-challenge. Horses in the vaccinated group were protected from leucopenia due to EHV4 disease and had higher WBC and lymphocyte counts than those in the control group (P<0.05).

Discussion and Conclusions

In this study, moderate and adequate clinical signs of EHV-4 infection were seen after challenge. Significantly fewer clinical signs of nasal exudate were seen in vaccinated horses on Days 6-10 and Day 14 post-challenge. Conjunctivitis scores were significantly lower in vaccinated horses on Days 7, 9, 10, 13, and 14 post-challenge. Despite the adequate display of clinical signs following challenge, virus shedding in nasal swab samples was infrequent following this EHV-4 challenge. Nasal swabs were examined by virus isolation in cell culture.

Significant group effects for WBCs and lymphocytes were seen on Days 4-6 (WBC) and Days 4-5 (lymphocytes) with vaccinated animals showing higher WBC and lymphocyte counts than control horses. These values establish that control horses did succumb to the immunosuppression brought on by infection with Herpesvirus, and also demonstrate that vaccination with a cross-protective strain of EHV-1 allowed vaccinated horses to be more refractive to the immunosuppressive properties of Herpesvirus infection. Additionally, horses in the vaccinated group had higher serum neutralization titers on Days 35, 42 and 49 than those in the control group

Data from this study confirm that horses vaccinated with a multi-component vaccine containing EHV-1 demonstrate cross-protective immunity when challenged with a heterologous EHV-4 challenge organism.

Example 4

This example is to illustrate the efficacy of the combination vaccine of the present invention as well as duration of immunity.

Materials and Methods

The influenza viral antigen used in the vaccine evaluated in this study was produced on Madin Darby Canine Kidney (MDCK) cells. Following growth, viral fluids were filtered, formalin inactivated, and concentrated. The inactivated viral fluids were tested for residual live virus after inactivation. On completion of satisfactory residual live virus testing the inactivated viral fluids were then used to formulate a vaccine which also contained inactivated Venezuelan, TC-83 strain (ATCC Accession No. PTA-9411), Eastern, NJO strain (ATCC Accession No. PTA-9412), and Western, Fleming strain (ATCC Accession No. PTA-9410), equine encephalomyelitis viruses, inactivated EHV-1 (ATCC Accession No. PTA-9525), inactivated influenza A/equine-2/Kentucky/95 (ATCC Accession No. PTA-9523) and influenza A/equine-2/NewMarket/2/93 (ATCC Accession No. PTA-9524) viruses, inactivated West Nile Virus, Horse Origin 2005 (ATCC Accession No. PTA-9409), and tetanus toxoid.

Vaccine was formulated to appropriate specifications for all antigens included in the product. Influenza A/equi-2/Ohio/03 (ATCC Accession No. PTA-9522) antigen was added to the vaccine at a pre-inactivation titer of 10^(6.7) TCID₅₀/mL.

The final formulated vaccine contains the following ingredients per 1 mL dose:

EHV-1 10^(7.0-9.0) TCID₅₀/mL Influenza A2/Ohio/03 10^(6.7-9.5) TCID₅₀/mL Influenza A2/KY/95 10^(6.7-9.5) TCID₅₀/mL Influenza A2/NewMarket/2/93 10^(6.7-9.5) TCID₅₀/mL Tetanus Toxoid 5-10 CPU Eastern Equine Encephalomyelitis 10^(6.7-9.2) TCID₅₀/mL Western Equine Encephalomyelitis 10^(6.7-9.2) PFU/mL Venezuelan Equine Encephalomyelitis 10^(6.7-9.2) TCID₅₀/mL West Nile Virus 10^(7.0--9.0) TCID₅₀/mL Adjuvant (preferably mineral oil) 100-200 μl Glycerol 100-200 μl EDTA 240 mM solution 10-20 μl Diluent - DMEM containing q.s. Gentamicin (30 μg/mL of diluent volume) Formaldehyde (0.1-0.2% of diluent volume)

Twenty-six (26) horses, 4-5 months of age, were used in this study. Fifteen horses served as vaccinates and eleven horses were mock-vaccinated control horses.

Vaccine was administered intramuscularly in a 1 mL dose volume to each of 15 horses in the vaccinate group. Eleven horses in the control group received a 1 mL dose of adjuvanted DMEM (Lot 004) containing excipients used in the 9-way vaccine (Gentamicin and formaldehyde) but no antigens. Challenge inoculation of virulent influenza A/equi-2/Ohio/03 strain virus was performed 4 months post-booster vaccination.

Serum samples for serological evaluation were collected from the vaccinated and control horses prior to initial vaccination, at 21 days post first dose vaccination (day of booster vaccination), on the day of challenge, and at 7 and 14 days post challenge. Body temperature, whole blood samples, and nasal swabs were obtained from each horse on the day of challenge, and daily throughout the 10 day post-challenge observation period for a total of 11 observation days. Clinical data was also recorded daily for each horse for the 11-day observation period.

Challenge

The challenge virus seed of Influenza A/equi-2/Ohio/03 was produced in eggs. Challenge virus was diluted on the morning of challenge 1:20 with tissue culture media to affect a titer sufficient to cause clinical influenza in the non-vaccinated challenged horses.

Sedivet® (romifidine hydrochloride), a sedative and analgesic, was administered intravenously to each horse prior to challenge at a dosage of 50 μg/kg of body weight. Each horse was then challenged with influenza A/equi-2/Ohio/03 virus. The challenge virus was administered intranasally as an aerosol produced by a nebulizer into an Equine AeroMask (Trudell Medical International, Ontario, Canada) by the following method:

Four milliliters of challenge virus were placed into the nebulizer cup in the AeroMask device. A pressure hose was fitted from an air compressor to the inlet port of the nebulizer. The outlet tube was then inserted into the AeroMask attached to the head of the horse being challenged and air pressure was applied to the inlet port. During this time approximately two milliliters of challenge virus fluid was aerosolized directly into the nostrils of the horse being challenged.

Temperature

Daily rectal temperatures were recorded for each of the 26 vaccinated and control horses on Day of Challenge and for 10 days post challenge by means of a calibrated, electronic thermometer (GSA Electronics) probe. The daily rectal temperatures were recorded in degrees Fahrenheit (° F.).

White Blood Cell Counts

Venous blood from each of the 26 vaccinated and control horses was collected daily on the Day of Challenge and for 10 days post-challenge directly into a vacutainer Disodium EDTA tube for WBC counts.

Nasal Exudate Evaluation

All nasal exudate observations were made prior to collection of nasopharyngeal swabs. On the Day of Challenge and for 10 days post challenge, the nasal passages and muzzle of each of the 26 vaccinated and control horses were examined and graded using the grading and scoring description listed below.

The scoring grades of 0 through 6 were assigned on the basis of the severity of the disease indicated by each of the following classification:

TABLE 5 Scoring Grades Score sheet Score Description of symptoms designation 0 Essentially normal indicates the horse was clean and EN essentially free of nasal exudate 1 Slight clear serous discharge that may be frequently C-1 observed in both diseased and normal horses 2 Moderate clear serous discharge is indicative of a definite C-2 increase in volume over that normally observed 3 Copious clear serous discharge that is generally observed C-3 only in diseased horses 1.5 Very slight mucopurulent discharge indicates that mucus VSM was definitely present in small amounts in either one or both nostrils 2 Slightly mucopurulent is a discharge easily observed in one SM or both nostrils 4 Moderately mucopurulent indicates that mucoid discharges MM were present in large quantities in both nostrils 6 Heavy mucopurulent indicates that copious amounts of a HM mucoid discharge filled both nostrils Coughing

Episodes of coughing on each observation day were counted for each horse during the entirety of the observation period, whether or not the individual animal was being examined by the investigator at that time. Observers other than the investigator recorded the number of episodes of coughing of each individual horse during the observation period. Scoring of coughing episodes was actual counts of coughing episodes per horse.

Conjunctivitis

Conjunctivitis was evaluated daily at the time of nasal exudate evaluation. Conjunctivitis scores were recorded as 0=normal; 1=mild to moderate conjunctivitis and 2=severe conjunctivitis.

Nasopharyngeal Viral Isolation/Hemagglutination (HA) Methods

On each observation test day each nasal passage of each vaccinated and control was sampled deeply by means of sterile swabs. On collection, each of two swabs was immediately placed in a single tube containing 4 mL of chilled transport medium (Dulbecco's Minimal Essential Medium (DMEM) supplemented with 2% FBS, 2× Pen/Strep, 2× Amphotericin B).

For isolation of virus, the tubes were mixed, the swabs aseptically removed, and the medium centrifuged at 1500 rpm for 10 to 15 minutes to remove particulates. Medium was filtered through a 0.2μ syringe filter prior to inoculation on tissue culture cells. After filtration, 4-6% of sterile 85% sucrose solution was added to each sample for freezing at −80° C. in order for all samples to be tested concurrently.

All samples were tested in sterile flat bottom microtiter plates using five wells per dilution and a 4 well dilution series for each of the 5 test wells. Upon thawing, 22 μL of the clarified sample medium was used to inoculate one day old monolayer of MDCK-S cells from which the growth medium had been aseptically removed and replaced with 200 μl of influenza growth medium (DMEM containing 5-10 units/mL of 10,000 U stock solution Porcine Trypsin, 2 mM L-glutamine, 1× Pen-Strep and 1× Amphotericin B). The plates were then incubated at 35° C. in a CO₂ incubator for 5-7 days. After the 5-7 day incubation period, 50 μl from a of the titration plates were transferred directly into a labeled 96 well vinyl HA plate. Chicken red blood cells were added to each well and allowed to settle for 30-90 minutes at room temperature. Wells were read for positive agglutination as evidence of presence of equine influenza virus.

Hemagglutination Inhibition (HI) Testing Procedure

Serum samples were prepared by dispensing 0.15 ml of each sample into a test tube and extracting with 0.3 mL of 0.01M Sodium Periodate Solution at room temperature for 15 minutes. Glycerol Solution 3% (0.125 mL) was added to each tube, mixed and incubated at room temperature for 15 minutes. All samples were then heat-inactivated at 56° C. for 30 minutes.

A 0.5% solution of chicken red blood cells was prepared in PBS (SAFC catalog number 59321C) and standardized to an optical density of 0.5 at 550 nm.

Extracted serum samples were tested in duplicate in U bottom polystyrene plates using a 2-fold dilution scheme in PBS ranging from 1:4 to 1:256, 25 ul per well. Influenza A/Equi2/Ohio03 stock virus (25 μL) was added to serum sample dilution. Plates were gently tapped to mix, and incubated at room temperature for 30 minutes. After incubation, chicken red blood cells were added to each well and incubated undisturbed at room temperature for 1 to 1.5 hours. Results were read by observing plates for presence or absence of agglutinated red blood cells in each well. Antibody titer was determined as the highest dilution of serum at which agglutination did not occur.

Results and Conclusions

When pooled across all timepoints post-challenge, vaccinated animals had lower total clinical scores than the control animals. When the total daily scores were summed over the post-challenge period, horses in the vaccinated group had lower total scores than those in the control group (P<0.05). The mitigated fraction was estimated to be 0.6485 (95% ASE CI: 0.3258, 0.9712).

TABLE 6 Total Clinical Score Vaccination Group by day Outcome variable group Day interaction Total clinical score¹ <0.0001 <0.0001 0.1321 ¹The GLIMMIX procedure would not converge, thus an ANOVA approach was used to evaluate the effect of vaccination over time after challenge. Results were interpreted through the bolded values.

TABLE 7 Mitigated fraction - total cumulative clinical score Mitigated fraction² Control Vaccinate P-value¹ (95% ASE CI) Total cumulative 18.36³ 9.93 0.0055 0.6485 clinical score² (0.3258, 0.9712) ¹P-value from Wilcoxon's rank sum test ²Nasal discharge score, conjunctivitis score and coughing score were summed with day and across all time points for each animal then ranked for the estimation of the mitigated fraction. ³Mean rank Nasal Discharge

The main effect of vaccination was statistically significant and reduced nasal discharge due to the influenza challenge. When pooled across all time points post-challenge, vaccinated animals had lower nasal discharge scores than the control animals.

TABLE 8 Nasal Discharge Score Vaccination Group by day Outcome variable group Day interaction Nasal discharge score¹ 0.0012 <0.0001 0.4627 ¹The GLIMMIX procedure would not converge, thus an ANOVA approach was used to evaluate the effect of vaccination over time after challenge. Results were interpreted through the bolded values. Conjunctivitis

For conjunctivitis, the main effect of vaccination was statistically significant. When pooled across all time points post-challenge, vaccinated animals had reduced conjunctivitis due to influenza infection as demonstrated by lower conjunctivitis scores than the control animals.

TABLE 9 Conjunctivitis Score Vaccination Group by day Outcome variable group Day interaction Conjunctivitis score¹ 0.0187 0.0001 0.2498 ¹The GLIMMIX procedure would not converge, thus an ANOVA approach was used to evaluate the effect of vaccination over time after challenge. Results were interpreted through the bolded values. Coughing

Vaccine also protected against the cough resulting from equine influenza infection. Vaccinated animals had lower scores (P<0.05) on Days 3, 5, 7, 8, and 9 post-challenge than control animals.

TABLE 10 Coughing Score Vaccination Group by day Outcome variable group Day interaction Coughing score¹ 0.0004 0.0009 0.0275 ¹The GLIMMIX procedure would not converge, thus an ANOVA approach was used to evaluate the effect of vaccination over time after challenge. Results were interpreted through the bolded values. Virus Shedding (Nasal Swabs)

The vaccination also reduced the percent of horses shedding virus (P<0.05). The figure below represents that the percentage of vaccinated animals shedding virus was lower (P<0.05) on Days 3, 4, and 5 post-challenge than control animals.

TABLE 11 Mitigated fraction - days virus shedding Mitigated fraction² Control Vaccinate P-value¹ (95% ASE CI) Days virus 2³ 0 0.0004 0.7939 positive^(2,3) (0.5343, 1.0000) ¹P-value from Wilcoxon's rank sum test ²The number of days of viral shedding was calculated then ranked for the estimation of the mitigated fraction. Asymptotic standard errors (ASE) were used to estimate the 95% confidence intervals (CI). ³The median number of days positive results was obtained from the virus isolation assay. HI Titers

The vaccine was also effective in eliciting protective antibody titers to equine influenza virus. Statistically significant higher titers in the vaccinated horses were seen on Day 36 (relative to vaccination), Day 154 (the day of challenge), 159 and 164. Horses in the vaccinated group had higher titers on each of these days than those in the control group (P<0.05).

WBC and Lymphocyte Counts

The vaccination also protected horses from reduction in white blood cell counts seen following influenza virus challenge. (P<0.05). Vaccination with the combination vaccine provided statistically significant protection that was seen on Days 2 and 7 for WBC counts, and Days 2, 6, 7, and 8 post-challenge. Horses in the vaccinated group had higher WBC and lymphocyte counts than those in the control group (P<0.05). A four month Duration of Immunity challenge was performed to demonstrate efficacy of the influenza virus fractions of a multi-component vaccine that included West Nile Virus vaccine (Encephalomyelitis-Rhinopneumonitis-Influenza-West Nile Virus Vaccine, Eastern, Western & Venezuelan, Killed Virus, Tetanus Toxoid) containing 3 Equine influenza A/equi-2 virus strains, ATCC Accession Nos. PTA-9522, PTA-9523, and PTA-9524, each of which is currently relevant in the equine population of the Americas, Europe and Asia. Twenty-six horses (15 vaccinates and 11 controls) were vaccinated twice in 3 week intervals with a 1 mL dose of vaccine, or were mock vaccinated with adjuvanted media components of the vaccine without viral antigen. Four months post-booster vaccination, horses were challenged with a virulent live Equine Influenza A/equi-2/Ohio03 virus. This virulent virus is the current Equine Influenza A/equi-2 strain recommended for inclusion into vaccines by OIE and is currently recognized as the most pertinent strain involved in outbreaks in the United States.

Results from this 4-month DOI challenge study show significant protective effects from challenge by vaccination with the test vaccine, a combination West Nile Virus vaccine with flu and other pertinent equine antigens. Importantly, vaccinated horses displayed statistically lower total clinical signs of influenza virus (nasal discharge, conjunctivitis, and coughing, P=0.0055) with a mitigated fraction estimated to be 0.6485 (95% ASE CI: 0.3258, 0.9712). Additionally, viral shedding was statistically lower in vaccinated horses than control horses (P=0.0004) with a mitigated fraction estimated to be 0.7939 (95% ASE CI: 0.5343, 1.0000). Hemagglutination inhibition titers were significantly higher in vaccinated horses than control horses, and white blood cell and lymphocyte counts remained significantly higher in vaccinated horses on multiple days of the study over those of control horses. No differences in rectal temperature were determined between the two groups.

In conclusion, the data from this study demonstrate that administration of 2×1 mL intramuscular doses of this West Nile Virus combination vaccine administered at a 21 day interval to foals 4 to 5 months of age protected against virulent challenge with the Equine Influenza A/equi-2/Ohio03 virus and provided a duration of immunity of at least 4 months for this product.

Example 5

This example illustrates the efficacy of an immunogenic composition of the present invention when challenged with (Equine Herpes Virus Type 1) EHV-1.

Materials and Methods

The EHV-1 viral antigen used in the vaccine evaluated in this study was produced on Madin Darby Bovine Kidney (MDBK) cells. Following growth, viral fluids were filtered, BPL inactivated, and concentrated. The inactivated viral fluids were tested for residual live virus after inactivation. On completion of satisfactory residual live virus testing, the inactivated viral fluids were then used to formulate a vaccine which also contained inactivated Venezuelan Equine Encephalomyelitis, TC-83 strain (ATCC Accession No. PTA-9411) Eastern Equine Encephalomyelitis, NJO strain (ATCC Accession No. PTA-9412) and Western Equine Encephalomyelitis, Fleming strain (ATCC Accession No. PTA-9410) viruses, inactivated influenza A/equine-2/Kentucky/95 (ATCC Accession No. PTA-9523), influenza A/equine-2/NewMarket/2/93 (ATCC Accession No. PTA-9524) and influenza A/equine-2/Ohio/03 (ATCC Accession No. PTA-9522) viruses, inactivated West Nile Virus (ATCC Accession No. PTA-9409) and tetanus toxoid.

Vaccine was formulated to minimum specifications for all antigens included in the product. EHV-1 antigen was added to the vaccine at a pre-inactivation titer of 10^(7.0) TCID₅₀/mL.

The final formulated vaccine contains the following ingredients per 1 mL dose:

EHV-1 10^(7.0-9.0) TCID₅₀/mL Influenza A2/Ohio/03 10^(6.7-9.5) TCID₅₀/mL Influenza A2/KY/95 10^(6.7-9.5) TCID₅₀/mL Influenza A2/NewMarket/2/93 10^(6.7-9.5) TCID₅₀/mL Tetanus Toxoid 5-10 CPU Eastern Equine Encephalomyelitis 10^(6.7-9.2) TCID₅₀/mL Western Equine Encephalomyelitis 10^(6.7-9.2) PFU/mL Venezuelan Equine Encephalomyelitis 10^(6.7-9.2) TCID₅₀/mL West Nile Virus 10^(7.0--9.0) TCID₅₀/mL Adjuvant (preferably mineral oil) 100-200 μl Glycerol 100-200 μl EDTA 240 mM solution 10-20 μl Diluent - DMEM containing q.s. Gentamicin (30 μg/mL of diluent volume) Formaldehyde (0.1-0.2% of diluent volume)

Forty (40) horses, 4-5 months of age, were used in this study. Horses were randomly assigned to either vaccinate or control groups and were micro-chipped and then vaccinated. Twenty horses served as vaccinates and twenty horses were mock-vaccinated control horses. All horses had negative to low (<1:6) EHV-1 serum neutralization (SN) titers prior to initiation of the study, indicative of horses susceptible to infection.

Vaccine was administered intramuscularly in a 1 mL dose volume to each of 20 horses in the vaccinate group. Twenty horses in the control group received a 1 mL dose of adjuvanted DMEM (Lot 004) containing excipients used in the 9-way vaccine (Gentamycin and formaldehyde) but no antigens. Challenge inoculation of virulent EHV-1 A183 strain virus was performed 15 days post-booster vaccination.

Serum samples for serological evaluation were collected from the vaccinated and control horses prior to initial vaccination, at 21 days post first dose vaccination (day of booster vaccination), on the day of challenge, and at 7 and 14 days post challenge. Body temperature, whole blood samples, and nasal swabs were obtained from each horse on the day of challenge, and daily throughout the 14 day post-challenge observation period for a total of 15 observation days. Clinical data was also recorded daily for each horse for the 15-day observation period.

Challenge Procedure

Challenge Virus

The original challenge virus seed used in this challenge study was the first passage of the original seed virus on Equine Dermal (ED) cells. This challenge virus was harvested and frozen at a titer of 10^(6.2) TCID₅₀/mL.

Intranasal Challenge Method

Sedivet® (romifidine hydrochloride), a sedative and analgesic, was administered intravenously to each horse prior to challenge at a dosage of 50 μg/kg of body weight. Each horse was then challenged with approximately 10^(6.5) TCID₅₀ of EHV-1 strain. The challenge virus was administered intranasally as an aerosol produced by a nebulizer into an Equine AeroMask (Trudell Medical International, Ontario, Canada) by the following method:

A pressure hose was fitted from an air compressor to the inlet port of the nebulizer. The outlet tube was then inserted into the AeroMask attached to the head of the horse being challenged and approximately 10 psi of air pressure was applied to the inlet port for four minutes. During this time approximately two milliliters of a 10^(6.2) TCID₅₀/mL challenge virus fluid was aerosolized directly into the nostrils of the horse being challenged.

Pre and Post Challenge Evaluation Parameters

Temperature

Daily morning rectal temperatures were recorded for each of the 40 vaccinated and control horses on Day of Challenge and for 14 days post challenge by means of a calibrated, electronic thermometer (GSA Electronics) probe. The daily rectal temperatures were recorded in degrees Fahrenheit (° F.).

White Blood Cell Counts

Venous blood from each of the 40 vaccinated and control horses was collected daily on the Day of Challenge and for 14 days post-challenge directly into a vacutainer Disodium EDTA tube for WBC counts.

Nasal Exudate Evaluation

All nasal exudate observations were made prior to collection of nasopharyngeal swabs. On the Day of Challenge and for 14 days post challenge, the nasal passages and muzzle of each of the 40 vaccinated and control horses were examined and graded using the grading and scoring description listed below.

The scoring grades of 0 through 6 were assigned on the basis of the severity of the disease indicated by each of the following classification:

(EN) Essentially normal indicates the horse was clean and essentially free of nasal exudate, score, 0;

(C-1) Slight clear serous discharge that may be frequently observed in both diseased and normal horses, score 1;

(C-2) Moderate clear serous discharge is indicative of a definite increase in volume over that normally observed, score 2;

(C-3) Copious clear serous discharge that is generally observed only in diseased horses, score 3;

(VSM) Very slight mucopurulent discharge indicates that mucus was definitely present in small amounts in either one or both nostrils, score 1.5;

(SM) Slightly mucopurulent is a discharge easily observed in one or both nostrils, score 2;

(MM) Moderately mucopurulent indicates that mucoid discharges were present in large quantities in both nostrils, score 4; and

(HM) Heavy mucopurulent indicates that copious amounts of a mucoid discharge filled both nostrils, score 6.

Nasopharyngeal Viral Isolation Methods

On each observation test day each nasal passage of each vaccinated and control was sampled deeply by means of a sterile swabs. On collection, each of two swabs were immediately placed in a single tube containing 4 mL of chilled transport medium (Dulbecco's Minimal Essential Medium (DMEM) supplemented with 2% FBS, 2× Pen/Strep, 2× Gentamicin, and 2× Amphotericin B).

For isolation of virus, the tubes were mixed, the swabs aseptically removed, and the medium centrifuged at 1500 rpm for 10 minutes to remove particulates. Medium was filtered through a 0.2μ syringe filter prior to inoculation on tissue culture cells. One mL of the clarified transport medium was used to inoculate a 2 cm² one day old monolayer of ED cells grown in a 24 well tissue culture plate from which the growth medium had been aseptically removed. Following inoculation, the inoculum was allowed to adsorb on the cell monolayer for one hour at 37° C. in a humidified incubator containing a 5% CO₂ atmosphere. After the absorption period, an additional 1 mL of re-feed medium (DMEM containing 2-5% fetal bovine serum (FBS), 2 mM L-glutamine and 3× Gentamicin and 2× Amphotericin B) was added to each well. Following addition of re-feed media the plates were then incubated at 37° C. in a CO₂ incubator. Each test and control tissue culture well was examined microscopically for 7 days for signs of cytopathic effect (CPE) typical of the EHV-1 A183 challenge virus. Wells that were negative at the end of the 7 day observation period were subcultured onto fresh cells and observed for an additional 7 days.

WBC Buffy Coat Virus Isolation

Venous blood from each of the 40 vaccinated and control horses was collected on the Day of Challenge and daily for 14 days post-challenge by vacutainer into a Disodium EDTA tube. After permitting gravity sedimentation of the erythrocytes in the tube of EDTA anti-coagulated blood, the plasma and white blood cells were pipetted off and placed in a sterile 5 mL snap-cap tube. The plasma and white blood cell mixture was centrifuged at 1500 RPM for 10-15 minutes to pellet the white blood cells. The pellet was washed twice with 3 mL of phosphate buffered saline (PBS) containing 2× Pen/Strep, 2× Gentamicin, and 2× Amphotericin B. Cells were then suspended in 4 mL of DMEM supplemented with 2% fetal bovine serum (FBS) and 2× Pen/Strep, 2× Gentamicin, and 2× Amphotericin B. One mL buffy coat suspension was used to inoculate a 2 cm² one day old monolayer of ED cells grown in a 24 well tissue culture plate from which the growth medium had been aseptically removed. Following inoculation, the inoculum was allowed to adsorb on the cell monolayer for one hour at 37° C. in a humidified incubator containing a 5% CO₂ atmosphere. After the adsorption period, an additional 1 mL of re-feed medium (DMEM containing 5-7% fetal bovine serum (FBS), 2 mM L-glutamine and 1× Gentamicin was added to each well. Following addition of re-feed media the plates were then incubated at 37° C. in a CO₂ incubator. Wells could not be observed microscopically due to large volume of white blood cells settled on the monolayer. Therefore, at the end of 7 days, all wells were subcultured onto fresh ED cells using 0.5 ml of the 1^(st) passage as inoculum. The subculture was observed for 7 days for CPE typical of challenge virus infection.

Serum Neutralization Testing Procedure

A standard microtiter serum neutralization test was employed in this study. All sera were tested in sterile flat bottom microtiter plates using five wells per dilution and an 8 well dilution series for each of the 5 test wells. Each of the 5 test wells contained 25 μl of serum dilution mixed with 25 μl of the indicator virus and 150 μl of a freshly planted ED cell suspension containing approximately 5×10⁴ cells. The test indicator virus used was EHV-1 subtype 1 strain A183. In all tests the indicator virus back titration titers ranged between 109 to 263 TCID₅₀/25 μl. Serum neutralizing antibody titers are expressed as Reed-Muench ID₅₀ titers.

For performance of the test, two-fold dilutions of each test serum was made in a sterile flat bottom microtiter plate using five replicate wells per test serum and an 8 well dilution series. Dilutions were made with an adjustable volume single or multi-channel pipetting instrument using sterile microtiter tips. The volume of serum added each of 5 wells of the first row was 50 μl. All other wells contained 25 μl of DMEM (no FBS). Following serial dilution down the plate, 25 μl was discarded from the last row. 25 μl of a pre-determined dilution of the indicator virus was added to each test well. Plates were then mixed and incubated for one hour at 37° C. in 5% CO₂. On conclusion of the incubation period, 150 μl of a suspension containing 5×10⁴ ED cells was added to each test and cell control well. The plates were incubated at 37° C. in a CO₂ incubator for 3 days, at which time plates were microscopically examined for CPE typical of EHV-1. Alternatively, any conventional or commercial available assay can be used or those of skill in the art would be able to follow the guidance herein.

Results and Conclusion

Nasal discharge scores, nasal shedding of EHV-1 and conjunctivitis scores were considered the primary outcome variables. All other outcomes were considered secondary.

TABLE 12 Summary of the statistical analysis (P-values) Vaccination Group by day Outcome variable group Day interaction Nasal discharge score¹ 0.0001 <.0001 <0.0001 Virus shedding¹ 0.0028 <0.0001 0.0863 Conjunctivitis score¹ 0.0020 <0.0001 0.0017 SN Titers <0.0001 <0.0001 <0.0001 WBC 0.3064 <0.0001 <0.0001 ¹The GLIMMIX procedure would not converge, thus an ANOVA approach was used to evaluate the effect of vaccination over time after challenge. Results were interpreted through the bolded values. Nasal Exudate Evaluation

The vaccination group by day interaction was statistically significant for the nasal discharge scores (P<0.05). Statistically significant group effects were seen on Days 4, 5 and on Days 7-11 post-challenge (lower nasal scores in the vaccinated group, P<0.05). When the daily scores were summed over the post-challenge period, horses in the vaccinated group had lower total scores than those in the control group (P<0.05). The mitigated fraction was estimated to be 0.7250 (95% ASE CI: 0.4886, 0.9614).

TABLE 13 Mitigated fraction - nasal discharge and conjunctivitis scores, nasal virus shedding (mean ranks) Mitigated fraction² Control Vaccinate P-value¹ (95% ASE CI) Nasal discharge 27.75 13.25 <0.0001 0.7250 (0.4886, 0.9614) Days shedding 24.43 15.78 0.0068 0.4925 virus² (0.1896, 0.7954) Conjunctivitis 25.80 15.20 0.0038 0.5300 (0.2463, 0.8137) ¹P-value from Wilcoxon's rank sum test ²Nasal discharge and conjunctivitis scores were summed across all time points then ranked for the estimation of the mitigated fraction. The number of days of viral shedding was calculated then ranked for the estimation of the mitigated fraction. Asymptotic standard errors (ASE) were used to estimate the 95% confidence intervals (CI).

TABLE 14 Mean nasal discharge score (N = 20 horses per group) Days post-challenge Control Vaccinated P-value¹ 0 0.00 0.00 1.0000 1 0.00 0.00 1.0000 2 0.15 0.00 0.6029 3 0.33 0.48 0.6029 4 1.08 0.23 0.0033 5 1.43 0.40 0.0004 6 1.05 0.55 0.0833 7 1.50 0.68 0.0044 8 1.68 0.63 0.0003 9 2.13 0.50 <.0001 10 1.58 0.80 0.0074 11 0.98 0.23 0.0095 12 0.90 0.35 0.0568 13 1.23 0.90 0.2599 14 0.93 0.43 0.0833 ¹The GLIMMIX procedure would not converge, thus an ANOVA approach was used to evaluate the effect of vaccination over time on the nasal discharge score. Conjunctivitis

The vaccination group, by day interaction, was statistically significant for the conjunctivitis scores (P<0.05). Statistically significant group effects were seen on Days 5 and 6, and on Days 9-14 post-challenge (lower scores in the vaccinated group, P<0.05). When the daily scores were summed over the post-challenge period, horses in the vaccinated group had lower total scores than those in the control group (P<0.05). The mitigated fraction was estimated to be 0.5300 (95% ASE CI: 0.2463, 0.8137).

TABLE 15 Mean conjunctivitis score (N = 20 horses per group) Days post-challenge Control Vaccinated P-value¹ 0 0.00 0.00 1.0000 1 0.00 0.00 1.0000 2 0.00 0.00 1.0000 3 0.05 0.00 0.7321 4 0.15 0.15 1.0000 5 0.70 0.25 0.0022 6 0.85 0.25 <.0001 7 0.75 0.65 0.4936 8 0.45 0.35 0.4936 9 0.50 0.15 0.0168 10 0.45 0.15 0.0403 11 0.50 0.05 0.0022 12 0.45 0.00 0.0022 13 0.45 0.05 0.0063 14 0.35 0.05 0.0403 ¹The GLIMMIX procedure would not converge, thus an ANOVA approach was used to evaluate the effect of vaccination over time. Virus Isolatin from Nasopharylngeal Swabs

The main effect of vaccination group was statistically significant (fewer animals shedding in the vaccinated group, P<0.05). When the number of days shedding was evaluated, horses in the vaccinated group had fewer days of virus shedding than those in the control group (P<0.05, Table 2). The mitigated fraction was estimated to be 0.4925 (95% ASE CI: 0.1896, 0.7954).

TABLE 16 Proportion virus shedding (nasal swab, N = 20 horses per group) Days post-challenge Control Vaccinated 0 0.00 0.00 1 0.00 0.00 2 0.05 0.05 3 0.05 0.10 4 0.20 0.05 5 0.25 0.15 6 0.45 0.25 7 0.45 0.35 8 0.50 0.10 9 0.45 0.15 10 0.25 0.00 11 0.35 0.10 12 0.30 0.10 13 0.15 0.00 14 0.05 0.00 White Blood Cell Counts

The vaccination group by day interaction was statistically significant for WBC counts (P<0.05, Table 1). Statistically significant group effects were seen on Days 2 and 3 post-challenge. Horses in the vaccinated group had higher WBC counts than those in the control group, indicating the vaccine prevented the horses from suffering the leucopenia caused by infection with EHV 1 (P<0.05).

TABLE 17 Mean WBC counts (N = 20 horses per group) Days post-challenge Control Vaccinated P-value¹ 1 14.0413 14.4887 0.6081 2 10.7963 14.1287 0.0001 3 11.1263 14.0687 0.0008 4 11.5013 13.1037 0.0667 5 10.7413 11.1987 0.6001 6 9.1063 9.4187 0.7203 7 10.1563 9.9037 0.7721 8 10.7813 10.6037 0.8386 9 11.1813 12.0737 0.3065 10 11.9713 12.4187 0.6081 11 12.6713 13.2137 0.5341 12 13.2913 13.5637 0.7549 13 14.7063 14.1737 0.5415 14 15.8463 14.4587 0.1121 ¹P-values from the ANOVA Serological Studies

Titers were log transformed prior to the statistical analysis. The vaccination group by day interaction was statistically significant for SN titers (P<0.05). Statistically significant group effects were seen on Days 35 (the day of challenge) and 7 and 14 days post-challenge (study days 42 and 49). Horses in the vaccinated group had higher titers than those in the control group (P<0.05).

TABLE 18 Geometric mean - serum neutralization titers (N = 20 horses per group) Study day Control Vaccinated P-value¹ 0 3.987 3.384 0.4005 21 3.190 2.624 0.3168 35 (day of challenge) 3.480 6.863 0.0006 42 3.519 19.252 <0.0001 49 33.153 187.417 <0.0001 ¹P-values from the ANOVA. Serum neutralization titers were log (natural) transformed prior to the statistical analysis. Results and Discussion

Respiratory disease caused by equine herpesvirus type 1 is usually an epidemic disease of naïve weanling and yearling horses that occurs in the first year of life, usually in the fall and winter months. Signs of acute infection include fever up to 106° F., viremia and leucopenia and/or neutropenia. Nasal discharge is usually evident during febrile periods of this first exposure. Natural infection by EHV-1 does not result in permanent immunity of the respiratory tract. Indeed, horses may be re-infected naturally every 3 to 6 months throughout life. After the first experience with this virus, re-infection results in production of virus, but usually without clinical signs of disease, resulting in carrier animals that act as natural reservoirs of the virus.

The equine herpesvirus-1 multi-component vaccine described in this report has been shown to be efficacious in reducing the respiratory manifestations, clinical symptoms and virus shedding from nasal exudate of horses challenged with a virulent heterologous strain of Equine Herpesvirus type 1. Reduction in shedding of virus from the respiratory route is important epidemiologically due to this being the natural route of exposure to naive animals as well as for re-infection of herd mates from those experiencing a natural infection. It was also a safe vaccine with no adverse reactions, either systemic or at the site of vaccine administration, observed following vaccine use in the study horses.

In this study, vaccination group by day interaction showed statistical significance for the primary outcome variables nasal discharge scores and conjunctivitis. Statistically significant group effects were seen in the vaccinate group for nasal discharge on Days 4, 5 and on Days 7-11 post-challenge. Group effects for conjunctivitis were also statistically significant on Days 5 and 6 and 9-14 with lower scores in the vaccinate group (P<0.05). This is significant epidemiologically because the EHV-1 virus is delicate and does not survive in the environment readily. Close contact is important for transmission of disease through nasal secretions containing virulent EHV-1 virus (Campbell and Studdert, 1983).

Importantly, another primary outcome variable in this study, virus shedding in nasal exudates, showed a main effect of vaccination as statistically significant (P<0.05). Horses in the vaccinated group also had statistically fewer days of virus shedding than those in the control group (P<0.05).

Serum neutralization titers were statistically significant after vaccination and throughout the challenge period in vaccinates versus control horses (P<0.05). Humoral immunity and mucosal antibodies may be important in determining whether an EHV-1 infection becomes a productive or limited infection event (Kidd, Smith, Hannant, et. al, 1994).

Example 6

This example illustrates the efficacy and 6 month duration of immunity of an immunogenic composition of the present invention when challenged with West Nile Virus.

Materials and Methods

The WNV viral antigen used in the vaccine evaluated in this study was produced on E vero cells as described in Example 1. A total of 15 horses were randomly divided into groups, one being a control group of 5 horses. The vaccinated group of 10 horses received 2 doses of vaccine at 21-day intervals cells. On completion of satisfactory residual live virus testing the inactivated viral fluids were then used to formulate a vaccine which also contained inactivated Venezuelan Equine Encephalomyelitis, TC-83 strain (ATCC Accession No. PTA-9411), Eastern Equine Encephalomyelitis, NJO strain (ATCC Accession No. PTA-9412), and Western Equine Encephalomyelitis, Fleming strain (ATCC Accession No. PTA-9410) viruses, inactivated influenza A/equine-2/Kentucky/95 (ATCC Accession No. PTA-9523), influenza A/equine-2/NewMarket/2/93 (ATCC Accession No. PTA-9524) and influenza A/equine-2/Ohio/03 (ATCC Accession No. PTA-9522) viruses, inactivated West Nile Virus (ATCC Accession No. 9409) and tetanus toxoid. Vaccine was formulated to minimum specifications for all antigens included in the product.

The final formulated vaccine contains the following ingredients per 1 mL dose:

EHV-1 10^(7.0-9.0) TCID₅₀/mL Influenza A2/Ohio/03 10^(6.7-9.5) TCID₅₀/mL Influenza A2/KY/95 10^(6.7-9.5) TCID₅₀/mL Influenza A2/NewMarket/2/93 10^(6.7-9.5) TCID₅₀/mL Tetanus Toxoid 5-10 CPU Eastern Equine Encephalomyelitis 10^(6.7-9.2) TCID₅₀/mL Western Equine Encephalomyelitis 10^(6.7-9.2) PFU/mL Venezuelan Equine Encephalomyelitis 10^(6.7-9.2) TCID₅₀/mL West Nile Virus 10^(7.0-9.0) TCID₅₀/mL Adjuvant (preferably mineral oil) 100-200 μl Glycerol 100-200 μl EDTA 240 mM solution 10-20 μl Diluent - DMEM containing q.s. Gentamicin (30 μg/mL of diluent volume) Formaldehyde (0.1-0.2% of diluent volume)

Fifteen horses were used in this study. Horses were randomly assigned to either vaccinate or control groups and then vaccinated. Ten horses served as vaccinates and five horses were mock-vaccinated control horses.

The vaccine was administered intramuscularly in a 1 mL dose volume to each of the horses in the vaccinate group. Each control received a 1 mL dose of adjuvanted DMEM containing excipients used in the 9-way vaccine (gentamycin and formaldehyde) but no antigens.

All groups were challenged approximately 6 months following vaccination with intrathecal inoculation of 1 ml PBS containing approximately 10⁵ pfu of a heterologous strain of WNV (NY99, 4132, crow isolate). The challenge was conducted under ketamine-xylazine anesthesia.

Horses were monitored for a maximum of 14 days.

Results and Discussion

Viremia after challenge was considered the primary outcome variable in this study. The horses that had been vaccinated were 90% protected from viremia after challenge in this study. In comparison, all of the 5 control horses demonstrated viremia for 3-5 days post-challenge.

In addition, serum neutralization titers of vaccinated horses were significantly higher than those of control horses after vaccination. All the vaccinated horses developed measurable serum neutralization titers following vaccination, whereas none of the controls displayed any titer to WNV. This study demonstrated that 2 doses of the experimental combination vaccine reliably and effectively stimulated protective serological serum neutralization titers.

Since viremia is a prerequisite before virus can cross the blood-brain barrier to cause WNV encephalitis, viremia is well justified as the primary parameter for evaluation of protection in an experimental study of this type.

The results demonstrated that an immunogenic reaction is induced in the animals that were administered the vaccine, and that the vaccine is effective at providing protection for at least 6 months following vaccination. The effectiveness of the vaccine was evidenced in this example by reduction in WNV viremia and by stimulation of high serum neutralization titers to WNV. Because this vaccine is comprised of unique constituents including a long lasting non-metabolizable adjuvant, is formulated in a low 1 mL dose volume to provide a high degree of safety as a highly immunogenic low passage whole inactivated virus WNV isolate of recent origin and high epidemiological prevalence (a North American Dominant WNV strain), and a WNV isolated from the tissues of an infected horse, it provides more comprehensive safety and long lasting effectiveness of at least 6 months duration than other vaccines currently available. Additionally, it has the effect of providing a safe vaccine when administered to animals, and in particular to horses.

Example 7

This example illustrates the efficacy of one embodiment of the immunogenic composition of the present invention including encephalomyelitis antigens with tetanus toxoid antigen.

Materials and Methods

Host animal and laboratory animal immunization/serology were evaluated to demonstrate efficacy of encephalomyelitis antigens and the tetanus toxoid antigen fraction in an Encephalomyelitis-Rhinopneumonitis-Influenza-West Nile Virus Vaccine, including Eastern, Western, and Venezuelan Encephalomyelitis, Killed Virus, and Tetanus Toxoid. The efficacy and lack of interference on equine encephalitis virus vaccines and tetanus toxoid fractions can be unequivocally demonstrated by laboratory animal potency testing of the combination vaccine. Demonstration of serological response following vaccination of horses is also indicative of vaccine-toxoid efficacy. Hence, both lab animal potency and host animal serology were used in this study to confirm the efficacy of the experimental vaccine. The vaccine was also evaluated for safety in animals including horses.

Horses 4-5 months of age, from non-vaccinated mares, were vaccinated with an efficacy serial of WNV combination vaccine containing inactivated Venezuelan Equine Encephalomyelitis Virus, TC-83 strain (ATCC Accession No. PTA-9411) Eastern Equine Encephalomyelitis Virus, NJO strain (ATCC Accession No. PTA-9412) Western Equine Encephalomyelitis Virus, Fleming strain (ATCC Accession No. PTA-9410) West Nile Virus (WNV), Horse Origin 2005 (ATCC Accession No. PTA-9409) Equine Herpesvirus Type 1 (ATCC Accession No. PTA-9525) (EHV-1), Influenza A/equine-2/Ohio/03 (ATCC Accession No. PTA-9522), Influenza A/equine-2/Kentucky/95 (ATCC Accession No. PTA-9523), Influenza A/equine-2/NewMarket/2/93 (ATCC Accession No. PTA-9524) and Tetanus Toxoid. Horses were vaccinated on Day 0 and Day 21 of the study. Blood samples were collected at Day 0, Day 21 and Day 35. Day 0 and Day 35 serological results are reported herein.

In addition, the same WNV combination vaccine used to vaccinate horses was tested for potency in guinea pigs. Data presented in this report collectively and definitively establish the efficacy of each antigen tested (EEE, VEE, WEE, tetanus) in this study and also confirm the safety of a WNV combination vaccine.

Bulk lots of EEE, WEE, and VEE viruses and tetanus toxoid were produced. Following growth, viral fluids were filtered, formalin inactivated, and concentrated. The inactivated viral fluids were tested for residual live virus after inactivation.

Inactivated viral and toxoid fluids described above were used to formulate a vaccine that also contained inactivated Equine Herpesvirus Type 1, inactivated influenza A/equine-2/Kentucky/95, influenza A/equine-2/NewMarket/2/93 and influenza A/equine-2/Ohio/03 viruses.

The vaccine was formulated to specifications for all antigens included in the product.

The final formulated vaccine contained the following ingredients per 1 mL dose:

EHV-1 10^(7.0-9.0) TCID₅₀/mL Influenza A2/Ohio/03 10^(6.7-9.5) TCID₅₀/mL Influenza A2/KY/95 10^(6.7-9.5) TCID₅₀/mL Influenza A2/NewMarket/2/93 10^(6.7-9.5) TCID₅₀/mL Tetanus Toxoid 5-10 CPU Eastern Equine Encephalomyelitis 10^(6.7-9.2) TCID₅₀/mL Western Equine Encephalomyelitis 10^(6.7-9.2) PFU/mL Venezuelan Equine Encephalomyelitis 10^(6.7-9.2) TCID₅₀/mL West Nile Virus 10^(7.0--9.0) TCID₅₀/mL Adjuvant (preferably mineral oil) 100-200 μl Glycerol 100-200 μl EDTA 240 mM solution 10-20 μl Diluent - DMEM containing q.s. Gentamicin (30 μg/mL of diluent volume) Formaldehyde (0.1-0.2% of diluent volume)

Forty horses, four to 5 months of age, were used in this study. Horses remained with their dams on pasture throughout the vaccination period and were weaned from their dams when the 2-week post-booster sera were collected. Horses were assigned to either one of the two treatment groups randomly as they were vaccinated intramuscularly (IM) with a 1.0 ml dose. The primary immunization was followed three weeks later by a 1.0 ml IM booster vaccination. Twenty horses received vaccine. Twenty horses received placebo.

Guinea pigs were also vaccinated with the same combination WNV vaccine.

Horses were vaccinated and serum samples collected using the following schedule:

TABLE 19 Vaccination and Serum Sampling Schedule Day of Test Activity 0 Collect pre-vaccination blood and give primary vaccination 21 Collect blood and give booster vaccination 35 Collect blood for final serology

Guinea pigs were vaccinated and serum collected using the schedule outlined by 9 CFR, 113.207(b) and 113.114(c.).

Sera from horses in this study were tested following general guidelines. The assay was modified to determine titers by testing at 1:2 and 1:10 dilutions for Day 0 samples and at 1:10 and 1:40 dilutions for the 2-week post-booster serum samples. Sera were tested for EEE, WEE and VEE antibody and were tested for Tetanus toxoid antibody.

Results and Discussion

Horse Serological Evaluation for EEE, WEE and VEE

At Day 0 of the Study, not all foals were sero-negative to encephalomyelitis viruses. Five of the vaccinated foals had significant (>1:10) residual maternal antibody to EEE virus. In addition, two of the vaccinated foals had residual maternal antibody (>1:10) to WEE virus. Despite existing and potentially interfering passively acquired, maternal antibody at the time of administration of the first dose of the WNV combination vaccine, titers for all three fractions increased substantially (>4 fold in 80% of horses tested for EEE, >4 fold in 90% of horses tested for WEE and >4 fold in 100% of horses tested for VEE) following vaccination, yet remained negative or low for the non-vaccinated foals. Individual foal data are presented below.

EEE, WEE and VEE Equine Serological Titers

TABLE 20 Plaque Reduction Neutralization Titration Day Day Day Day Day Day Test 0 35 0 35 0 35 Horse ID Article EEE EEE WEE WEE VEE VEE 1 V >10 >40 2 >40 <2 >40 2 V <2 >40 <2 10 <2 40 3 V <2 >40 <2 <10 <2 >40 4 V <2 >40 <2 10 <2 >40 5 V >10 >40 >10 >40 <2 >40 6 V >10 >40 <2 >40 NS 10 7 V <2 >40 <2 >40 <2 >40 8 V >10 >40 2 >40 <2 >40 9 V <2 >40 <2 >40 <2 >40 10 V <2 >40 <2 >40 <2 10 11 V <2 >40 <2 >40 <2 >40 12 V <2 >40 <2 >40 <2 40 13 V <2 >40 <2 >40 <2 >40 14 V <2 >40 <2 10 <2 >40 15 V >10 >40 >10 >40 2 >40 16 V 2 >40 <2 10 <2 >40 17 V <2 >40 <2 10 <2 >40 18 V <2 >40 <2 >40 <2 40 19 V <2 10 <2 >40 <2 >40 20 V 2 >40 <2 >40 <2 10 21 C <2 <10 <2 <10 <2 10 22 C <2 <10 <2 <10 <2 <10 23 C <2 <10 <2 10 <2 <10 24 C <2 <10 NS <10 <2 <10 25 C <2 <10 <2 <10 <2 <10 26 C <2 <10 <2 10 <2 <10 27 C <2 <10 <2 <10 <2 <10 28 C 2 <10 <2 <10 <2 10 29 C 2 <10 <2 10 <2 <10 30 C <2 <10 <2 <10 <2 <10 31 C <2 <10 <2 <10 <2 <10 32 C <2 <10 <2 <10 <2 <10 33 C >10 >40 <2 10 <2 <10 34 C <2 <10 <2 <10 <2 <10 35 C >10 10 2 <10 <2 10 36 C 2 <10 <2 <10 <2 <10 37 C <2 <10 <2 <10 <2 <10 38 C <2 <10 2 <10 <2 <10 39 C <2 10 <2 <10 <2 <10 40 C <2 >40 <2 <10 <2 <10

Guinea Pig Serological Evaluation for EEE, WEE, VEE and Tetanus Toxoid

Nine of ten guinea pigs vaccinated with the combination vaccine seroconverted satisfactorily at (≧1:40) to EEE virus. Ten of ten guinea pigs had satisfactory titers for VEE virus (≧1:4) and ten of ten guinea pigs seroconverted satisfactorily to WEE virus (≧1:40). Also a serum pool from 10 vaccinated guinea pigs was tested for tetanus antibody and was shown to be satisfactory with a value of 4.3 anti-toxin units/ml (AU/ml).

Guinea pig potency tests were completed and found to be satisfactory for all four antigens including tetanus toxoid, EEE, VEE, and WEE.

The vaccine was also administered to horses (20 vaccinates and 20 controls) via primary immunization followed by booster immunization 3 weeks later. Fourteen days post-booster vaccination, horses were bled and serum collected for all serological testing. Equine response to encephalomyelitis antigens was tested utilizing 2 dilutions (1:2 and 1:10 for Day 0 samples and 1:10 and 1:40 for Day 35 samples) in 24-well plates to determine antibody titers.

The satisfactory guinea pig potency testing conclusively establishes the efficacy of 4 antigens (VEE, EEE, WEE and tetanus toxoid) in the West Nile Virus combination vaccine as a 9-antigen-containing vaccine-toxoid. Furthermore, satisfactory potency results are substantiated and confirmed by host animal horse serology data in which vaccinated horses demonstrated a substantial rise in titer to each encephalitis virus fraction following vaccination. Additionally, the absence of observation of any adverse reactions in any of the vaccinated horses or guinea pigs confirms the safety of the WNV combination vaccine in animals.

Example 8

This example illustrates that a vaccine or immunogenic composition in accordance with the present invention has a duration of immunity of at least one year.

Materials and Methods

Host animal vaccination and challenge at least 1 year post-booster vaccination was used to confirm duration of immunity for the West Nile Virus antigen fraction in an Encephalomyelitis-Rhinopneumonitis-Influenza-West Nile Virus Vaccine, Eastern, Western & Venezuelan, Killed Virus, Tetanus Toxoid prepared from a North American Dominant isolate of WNV designated North American Equine E159 (NAEE159).

TABLE 21 The final formulated vaccine contains the following ingredients per 1 mL dose: Ingredients 1 mL Dose Eastern Equine Encephalomyelitis 10^(7.5-9.2) TCID₅₀/mL Western Equine Encephalomyelitis 10^(8.2-9.2) PFU/mL Venezuelan Equine Encephalomyelitis 10^(7.7-9.2) TCID₅₀/mL West Nile Virus (North American 10^(8.0-9.2) TCID₅₀/mL Dominant prepared from NAEE159) EHV-1 10^(7.0-9.0) TCID₅₀/mL Equine Influenza A2/Ohio/2003 10^(7.3-9.5) TCID₅₀/mL Equine Influenza A2/Kentucky/95 10^(7.3-9.5) TCID₅₀/mL Equine Influenza A2/NewMarket/2/ 10^(7.3-9.5) TCID₅₀/mL 93 Tetanus Toxoid 5-10 CPU Non-metabolizable Oil Adjuvant 100-200 μl Diluent - DMEM containing q.s. Gentamicin 30 μg/mL of diluent volume Formaldehyde 0.1% of diluent volume

Thirty horses (20 vaccinates and 10 controls), 4-5 months of age were used in this study. Horses were randomly assigned to one of two treatments and vaccinated intramuscularly (IM) with a 1.0 mL dose of the assigned vaccine or control product. The primary immunization was followed three weeks later by a 1.0 mL IM booster vaccination.

Horses were vaccinated once and then again about 30 days later. Horses were randomly assigned to either vaccine or control groups. Twenty horses received the vaccine group receiving VEWT/WNV/EHV-1/Influenza vaccine. Ten horses received adjuvanted DMEM containing excipients used in the vaccine (Gentamicin and formaldehyde) but no antigens. The non-metabolizable oil adjuvant used for all administrations was preferably mineral oil.

Challenge inoculation of the virulent heterologous WNV NY99 strain virus was performed 380 days post-booster vaccination. The second cohort of horses were challenged 408 days post-booster inoculation in a similar manner.

Serum samples for serological evaluation were collected from the vaccinated and control horses prior to initial vaccination, at 21 days post first dose vaccination (day of booster vaccination), monthly post-booster, on the day of challenge, and at 7 and 14 days post-challenge. Body temperature and serum samples were obtained from each horse on the day of challenge, twice daily on Days 1 through 6 post-challenge, and daily on Days 7-10 and Day 14 post-challenge. Clinical data was also recorded during those same time periods for the 15-day observation period.

The heterologous challenge virus, designated WNV NY99, was originally isolated from the brain of an infected crow (CDC, Ft. Collins, Colo.). On the day of challenge, the stock virus was thawed on ice and virus was diluted to the desired concentration in phosphate-buffered saline immediately prior to inoculation of horses.

Rectal temperatures were recorded for each of the vaccinated and control horses on the day before challenge, day of challenge and twice daily on days 1-14, then daily on Days 14-21 post challenge by means of a calibrated, electronic thermometer (GSA Electronics) probe. The daily rectal temperatures were recorded in degrees Fahrenheit (° F.).

Venous blood from each of the vaccinated and control horses was collected on the Day of Challenge, twice daily on Days 1-6, and daily on Days 7-10 and Day 14 days post-challenge by Vacutainer into an SST tube. After centrifugation, serum was aliquotted and frozen immediately.

Vero Cells were grown in 6-well plates to confluency. To perform the plaque assay, serial 10-fold dilutions of serum were prepared in 96-well plates in BA-1 medium (MEM salts containing 1% BSA, 250 mg/L sodium bicarbonate, 50 μl gentamicin and 2.5 μg amphotericin B/mL in 50 mM Tris, pH 7.6). Serum dilutions (0.1 mL) were inoculated into each well of the 6-well plate and incubated for 45-60 minutes with rocking every 15 minutes. After the incubation period, 2 mL of overlay (2× medium containing MEM without phenol red prepared at twice the normal concentration and supplemented with 4% FBS, 200 IU penicillin G/mL and 100 μg streptomycin/mL—warmed to 45° C.) was added to each well. Plates were incubated at 37° C.

Two days after inoculation, 2 mL of a second overlay containing 2× agarose prepared by mixing equal volumes of 2× medium and 2× agarose was added to each well. Plates were examined and plaque numbers recorded in each well on days 3, 4 and 5 following inoculation. The virus titer per mL of original material is calculated as the number of plaques in a well (or average of multiple wells inoculated with the same dilution) times the dilution for the well being counted multiplied by 10.

A standard microtiter serum neutralization test was employed in this study. All sera were tested in sterile flat bottom 96 well microtiter plates using five wells per dilution and an 8 well dilution series for each of the 5 test wells. Each of the 5 test wells contained 25 μL of serum dilution mixed with 25 μL of the indicator virus and 150 μL of a freshly planted Vero cell suspension containing approximately 4×10⁴ cells. The test indicator virus used was WNV NY99. Serum neutralizing antibody titers are expressed as Reed-Muench ID₅₀ titers.

For performance of the test, two-fold dilutions of each test serum were made in a sterile flat bottom microtiter plate using five replicate wells per test serum and an 8 well dilution series. Dilutions were made with an adjustable volume single or multi-channel pipetting instrument using sterile microtiter tips. The volume of serum added to each of 5 wells of the first row was 50 μL. All other wells contained 25 μL of DMEM (no FBS). Following serial dilution down the plate, 25 μL was discarded from the last row. 25 μL of a pre-determined dilution of the indicator virus was added to each test well. Plates were then mixed and incubated for one hour at 37° C. in 5% CO₂. On conclusion of the incubation period, 150 μL of a suspension containing 4×104 Vero cells were added to each test and cell control well. The plates were incubated at 37° C. in a CO₂ incubator for 5-7 days, at which time plates were microscopically examined for CPE typical of WNV.

Histopathology was evaluated by a Board Certified Veterinary Pathologist. The scoring system used to describe defects in the pons or medulla was as follows:

Score:

-   0=no significant lesions in section -   0.5=rare, small, multifocal glial nodules scattered throughout the     parenchyma -   1=mild, nonsuppurative encephalitis. This is characterized by mild     multifocal perivascular cuffs with lymphocytes and plasma cells and     a rare neutrophil and scattered multifocal glial nodules composed of     glial cells with a few mononuclear inflammatory cells. Occasionally     within this grade, there may be minimal perivascular cuffing and     more moderate scattered glial nodules. -   2=moderate nonsuppurative encephalitis characterized by moderate     lymphoplasmacytic perivascular cuffs around many vessels and     multifocal accumulations of glial nodules scattered throughout the     parenchyma -   3=severe nonsuppurative encephalitis characterized by severe and     thick lymphoplasmacytic perivascular cuffing with multiple scattered     glial nodules throughout the parenchyma     Results and Discussion

There were no adverse reactions to vaccine administration at either dosing time point. All 4 to 5 month old foals receiving the experimental vaccine were free of either systemic or injection site adverse reactions in the study. This confirms the excellent safety of the vaccine of the present invention against WNV containing North American Dominant WNV antigen prepared from isolate NAEE159.

Horse Challenge with Heterologous West Nile Virus

Viremia

Each of the 10 control horses (100%) were viremic for at least 1 day post-challenge, while only 2 of 20 horses (10%) in the WNV vaccine group were viremic.

Clinical Signs

Seven of the 10 horses (70%) in the control group developed signs of encephalomyelitis consistent with West Nile Virus infection. Each of these animals was viremic for at least one day during the challenge period. In the WNV vaccine group, 1 of the 20 horses (5%) developed signs consistent with West Nile Virus infection. Notably clinical signs progressed to death or euthanasia in 70% of the controls and only 5% of the vaccinates. All control mortalities were viremic, confirming fatal encephalitis due to WNV, whereas only one of two vaccinated animals that died was viremic during the challenge period.

Serum Neutralization Titers

All vaccinated horses responded favorably to the WNV vaccine by developing protective levels of serum neutralizing (SN) antibody following vaccination. Over one year following vaccination, 17 of 20 (85%) of vaccinated horses maintained protective SN titers. By contrast, none of the control horses developed rising SN titers prior to virulent WNV challenge. Also, all vaccinated horses displayed an anamnestic rise in SN titers following virulent WNV challenge

Histopathology

Severity scores were provided for both the medulla and pons. Also with regard to this efficacy parameter, WNV vaccine containing North American Dominant WNV antigen prepared from isolate NAEE159 proved highly effective. Among the control horses, 50% displayed severe lesions of WNV encephalitis whereas only 10% of vaccinates were similarly affected.

Discussion and Conclusions

The WNV vaccine was prepared from a viral isolate (North American Equine E159) obtained from a horse in 2005 during the North American pandemic when a specific dominant WNV genotype emerged. This genotype is characterized by a specific valine to alanine amino acid change at the 159^(th) amino acid in the envelope (E) protein of the virus (when compared to the publicly available sequence for the WNV-NY99 isolate having the ATCC Accession No. AF196835), which has made all such isolates more robust and prolific, thereby displacing other WNV isolates, and making this genotype dominant among disease-causing WNV isolates in North America. Because it was prepared from the dominant genotype, the vaccine used in this study is indicative of the unique safety and efficacy achievable with vaccine prepared from all such North American Dominant isolates with this E protein profile and resulting prolificacy. Notably, all previously tested WNV vaccines have been prepared from a less prolific isolate of differing genotype and E protein amino acid sequence, namely WNV NY99. Based on this difference in nucleic acid sequence, E protein amino acid sequence, viral prolificacy, and unique ability to cause a pandemic, the North American Dominant isolates are displacing or have displaced NY99 from the environment. The unique genotype and phenotype (prolificacy), and, most importantly, the overwhelming environmental presence of North American Dominant WNV isolates and the absence of WNV NY99 is compelling evidence for the superiority of the North American Dominant West Nile Virus vaccine. Such superiority is confirmed by the safety and efficacy of the vaccine as demonstrated in this challenge study using vaccine prepared from North American Dominant isolate North American Equine E159 (NAEE159) (ATCC Accession No PTA-9409).

In this study, 4 to 5 month old horses were safely and effectively vaccinated with a multi-component VEWT/WNV/EHV-1/Equine Influenza vaccine batched at an appropriate antigen amount with the WNV component being North American Dominant WNV antigen prepared from isolate NAEE159c (ATCC Accession No. PTA-9409).

Study horses were intrathecally challenged at least 380 days post-booster vaccination with 10⁵ PFU of a virulent heterologous West Nile Virus strain. Horses were evaluated for 14 days post-challenge for clinical signs (including temperature and mortality), viremia, serum neutralization titers, and histopathology scores from sections of the pons and medulla taken after euthanasia and necropsy.

Viremia after challenge and serum neutralization titers were key outcome variables in this study that were highly indicative of vaccine efficacy. Horses that had been vaccinated more than one year earlier with VEWT/WNV/EHV-1/Influenza Lot 916 were 90% protected from viremia after challenge in this study. In comparison, 100% of control horses demonstrated viremia post-challenge. Additionally, serum neutralization titers of vaccinated horses were significantly higher than those of control horses at 14 days post-challenge, and displayed an anamnestic response typical of an effective vaccine following heterologous, virulent WNV challenge.

In addition the vaccine containing North American Dominant WNV antigen prepared from isolate NAEE159 reduced clinical signs and mortality resulting from encephalomyelitis following heterologous challenge with virulent WNV. Vaccine efficacy at least one year following vaccination was also confirmed by reduction in lesions typical of WNV infection.

This study demonstrated for the first time that 2 doses of the experimental combination vaccine prepared at appropriate doses of antigen including North American Dominant WNV antigen prepared from isolate NAEE159 administered to foals 4 to 5 months of age safely, reliably and effectively stimulated protective serological serum neutralization titers that resulted in duration of immunity of at least one year with protection from viremia, clinical signs, mortality, and encephalitic lesions after virulent heterologous challenge with West Nile Virus.

Example 9

In this study, a combination vaccine was prepared using a North American Dominant isolate of WNV, North American Equine E159(NAEE159) (ATCC Accession No. PTA-9409). The 14-day post second-vaccination sera samples from the guinea pigs vaccinated with this Encephalomyelitis-Rhinopneumonitis-Influenza-West Nile Virus Vaccine, Eastern, Western & Venezuelan, Killed Virus, Tetanus Toxoid were collected and tested for West Nile Virus plaque reduction neutralization (PRN). The sera from the vaccinated guinea pigs were tested for neutralizing antibody to both a North American Dominant isolate of WNV and to WNV isolate NY99. Notably, the vaccine displayed superior activity in stimulating neutralizing antibodies to North American Dominant WNV, as opposed to NY99 WNV. These data support the conclusion of the superior efficacy of WNV vaccines prepared from North American Dominant WNV isolates as contrasted with earlier less effective vaccines prepared from or based on the NY99 WNV isolate.

Furthermore, a vaccine prepared from an additional North American Dominant isolate of WNV, North American Donkey E159 (NADE159) will similarly demonstrate, as described above, the superior efficacy of such vaccines over the former NY99 based vaccines. Hence, data from multiple North American Dominant isolates cultivated from different host species, originating from unique North American locations, and obtained at different times in North America will confirm the unexpected but superior efficacy of North American Dominant isolates of WNV for vaccine preparation.

The data from the plaque reduction neutralization assay also established that a vaccine prepared from a North American Dominant isolate of WNV that stimulates a titer of 1:12 or higher in vaccinated guinea pigs that provides 50% viral plaque reduction in at least 90% of vaccinated guinea pigs, correlates to vaccine protection against WNV challenge in the horse and provides for a duration of immunity of at least one year. West Nile Virus vaccination/challenge data in the horse at an antigen inclusion level of 10^(7.6-9.0) TCID₅₀ or higher per dose correlated with these guinea pig PRN titer results and confirmed the WNV immunizing dose that provides 1 year or longer duration of immunity in the horse. The corresponding dose in guinea pigs also stimulates serum neutralizing antibodies to a titer of at least 1:12 against North American Dominant WNV in guinea pigs.

Data presented in this report collectively demonstrate the unexpected efficacy of vaccines prepared from North American Dominant isolates of WNV, define the correlation between vaccine efficacy in the horse and guinea pig serum levels of neutralizing antibody, confirm that a 1:12 titer or higher in guinea pigs identifies an effective equine vaccine providing at least one year duration of immunity, and quite notably, demonstrate the superior efficacy of vaccines prepared from North American Dominant WNV as contrasted with NY99 WNV.

Materials and Methods

In order to demonstrate efficacy of the West Nile Virus antigen, prepared using a North American Dominant isolate of WNV, North American Equine E159(NAEE159) (ATCC Accession No. PTA-9409), in an Encephalomyelitis-Rhinopneumonitis-Influenza-West Nile Virus Vaccine, Eastern, Western & Venezuelan, Killed Virus, Tetanus Toxoid and to establish an effective dose measurable in horses or guinea pigs, host animal vaccination/challenge studies were performed in conjunction with guinea pig vaccination/serology studies. In this study, 14-day post second-vaccination sera samples from guinea pigs vaccinated with Encephalomyelitis-Rhinopneumonitis-Influenza-West Nile Virus Vaccine, Eastern, Western & Venezuelan, Killed Virus, Tetanus Toxoid were collected and tested. Additionally, a plaque reduction neutralization assay was developed to measure the titer correlated to protection against challenge in the host animal. This titer was determined to be 1:12 or higher in the guinea pig.

Vaccine Formulations

Experimental Serials (Protective Dose Vaccine)

Experimental Serials were formulated to confirm protective antigen specifications for all antigens in the vaccine.

TABLE 22 The final formulated vaccines contained the following ingredients per 1 mL dose: Ingredients 1 mL Dose Eastern Equine Encephalomyelitis 10^(7.5-9.2) TCID₅₀/mL Western Equine Encephalomyelitis 10^(8.2-9.2) PFU/mL Venezuelan Equine Encephalomyelitis 10^(7.7-9.2) TCID₅₀/mL West Nile Virus (North American 10^(7.3-9-2) TCID₅₀/mL Dominant prepared from NAEE159) EHV-1 10^(7.0-9.0) TCID₅₀/mL Equine Influenza A2/Ohio/2003 10^(7.3-9.5) TCID₅₀/mL Equine Influenza A2/Kentucky/95 10^(7.3-9.5) TCID₅₀/mL Equine Influenza A2/NewMarket/2/ 10^(7.3-9.5) TCID₅₀/mL 93 Tetanus Toxoid 5-10 CPU Non-metabolizable Oil Adjuvant 100-200 μl Diluent - DMEM containing q.s. Gentamicin 30 μg/mL of diluent volume Formaldehyde 0.1% of diluent volume

Experimental serial 916 was formulated for host animal vaccination studies. Experimental serial 916 is a multi-component vaccine containing VEWT-WNV-EHV-1 and 3 strains of equine influenza type A2 virus. Experimental serial 916 is batched at 10^(7.6-9.2) TCID₅₀/mL of West Nile Virus antigen North American Equine E159(NAEE159). It is a 1 mL dose vaccine in the horse.

This vaccine was also tested in guinea pigs at the time of host animal vaccinations to confirm the WNV efficacy and laboratory animal potency. Four replicate guinea pig sera dilution experiments were performed for experimental serial 916 to validate a guinea pig assay criterion for this one-year duration of immunity (DOI) vaccine.

Experimental Serial 507 (Comparative Efficacy Serial)

Data from Experimental Serial 507 is included in this report to demonstrate that serials formulated with a North American Dominant isolate of WNV antigen show superior efficacy, measured as guinea pig titers, of the relevant North American Dominant isolates of WNV as compared to the earlier NY99 isolate.

Guinea Pig Serological Evaluation

Sera were tested for WNV antibody as follows:

-   1) West Nile Virus Indicator Strain: North American Equine     E159(NAEE159) (ATCC Accession No. PTA-9409) & North American Donkey     E159 (NADE159) -   2) Growth medium for Vero Cells is DMEM+5% FBS, 2 mM L-glutamine and     30 μg/mL gentamycin -   3) Diluent for Test Serum is DMEM plus 30 μg/mL gentamycin -   4) Diluent for indicator virus working solution is DMEM+10% normal     guinea pig serum (specific to WNV assay) -   5) Guinea pig test sera is diluted 1:12 -   7) Use 4 mL overlay instead of 3 mL (specific to WNV assay) -   8) Titers are calculated using 50% plaque reduction -   9) Nine of ten vaccinated guinea pigs must have an antibody titer of     ≧1:12 to demonstrate efficacy, and negative guinea pigs must be <1:4     (same criteria as VEE assay in SAM).     Results and Discussion     Serological Evaluation for West Nile Virus     Experimental Serial 916 Replicate I West Nile Guinea Pig

Plaque Reduction Neutralization

Results Using North American Equine E159(NAEE159) as Indicator Virus

The study was initiated and the guinea pigs were bled 25 days later.

TABLE 23 Number of Plaques/Sera Dilution 916 (I) 2 3 4 6 8 12 16 32 64 GP1 0 2 2 4 5.5 2.5 17 14 11 GP2 6.5 9.5 11 14 9 11.5 13 20 22.5 GP3 7 5 6 9.5 10 9.5 11 10 16.5 GP4 7 5 4 4 1 6 15.5 9.5 12.5 GP5 6 4.5 9 7 17.5 13.5 12 16 17 GP6 1 1 2.5 7.5 3 8 19.5 19.5 20.5 GP7 9.5 8 8 15.5 17.5 21.5 36 17.5 20.5 GP8 5 3.5 7.5 7.5 14.5 11 26.5 26.5 27.5 GP9 0 2 7 6 7 12 9 10.5 11.5 GP10 4.5 4.5 5.5 11 22 8.5 23 29 30.5 # Passed 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 10/10 Neg. 68.5 64.5 72.5 93.5 68 82 89.5 78.5 71 Control 1 Neg. 72 61 87 69.5 70.5 85.5 77.5 69.5 88 Control 2 Virus Control Values: 99. 70, 68, 88, 77, 64 Virus Control Average Plaques: 79 Virus Control 50% Reduction: 39.5

TABLE 24 Experimental Serial 916 Replicate II West Nile Guinea Pig Plaque Reduction Neutralization Results Using North American Equine E159(NAEE159)as Indicator Virus Guinea Pigs were bled 35 days after the initiation of the study Number of Plaques/Sera Dilution 916 (II) 2 3 4 6 8 12 16 32 64 GP1 1 3 6 6 14.5 6.5 13.5 18 17.5 GP2 1.5 3.5 6.5 6.5 8.5 9.5 10.5 12.5 19 GP3 12 5.5 22 21 41.5 34 41 41 43.5 GP4 4 8.5 17.5 16.5 21 36.5 28 41.5 42.5 GP5 3.5 4.5 9.5 15 26.5 25.5 13.5 23 40 GP6 1 3 7 13.5 17.5 14 24.5 26 23 GP7 8 5.5 14.5 11.5 21.5 15.5 34 26.5 28 GP8 1 1.5 2.5 3.5 4 11 9 20 17.5 GP9 13.5 18 25.5 29.5 29.5 35.5 28 37.5 43 GP10 9 8 10.5 21.5 21 20.5 27 31.5 27.5 # Passed 10/10 10/10 10/10 10/10 9/10 10/10 9/10 8/10 6/10 Neg. 69.5 67 71.5 69.5 72.5 73 83 68 78 Control 1 Neg. 68 70.5 69 72.5 82.5 66 75 76 74 Control 2 Virus Control Values: 99. 70, 68, 88, 77, 64 Virus Control Average Plaques: 79 Virus Control 50% Reduction: 39.5

TABLE 25 Experimental Serial 916 Replicate III West Nile Guinea Pig Plaque Reduction Neutralization Results Using North American Equine E159(NAEE159)as Indicator Virus Guinea Pigs were bled 35 days after initiation Number of Plaques/Sera Dilution 916 (III) 2 3 4 6 8 12 16 32 64 GP1 0.5 1.5 0 0 0 1 4 6 3.5 GP2 0 0 1 0.5 0 0 0 0 0 GP3 7.5 9 9 16 17 13.5 12 18.5 23 GP4 2.5 0 0 3 2 2 3.5 1 2.5 GP5 13.5 15.5 18 18 19.5 24 16.5 21.5 33.5 GP6 6.5 15.5 31.5 10 29.5 26.5 28.5 31.5 32 GP7 14.5 12 17.5 20.5 19.5 29.5 21.5 16 22.5 GP8 21 24.5 36 28 34.5 30.5 27.5 29 26 GP9 0.5 0.5 3 4 6.5 5 10 9.5 18 GP10 2.5 7.5 11 8 12.5 9 20 10.5 17 # Passed 10/10 10/10 8/10 10/10 9/10 10/10 10/10 9/10 8/10 Neg. 73 61.5 79.5 53.5 58.5 78 57 70 63 Control 1 Neg. 55 54.5 64 52.5 58 68.5 66 67.5 79 Control 2 Virus Control Values: 51, 58, 61, 66, 78 Virus Control Average Plaques: 62 Virus Control 50% Reduction: 31

TABLE 26 Experimental Serial 916 Replicate IV West Nile Guinea Pig Plaque Reduction Neutralization Results Using North American Equine E159(NAEE159)as Indicator Virus Guinea Pigs were bled 30 days after the initiation of the study Number of Plaques/Sera Dilution 916 (IV) 2 3 4 6 8 12 16 32 64 GP1 11.5 7 5.5 20.5 12 17.5 22.5 20 25 GP2 31 21.5 20.5 36.5 32 30 27 15 28.5 GP3 16 20.5 18 23.5 21.5 16 35.5 16.5 15 GP4 1 2 6.5 7 11 15 19 14 18.5 GP5 4 1 9.5 12 20 17 24.5 19.5 23.5 GP6 0 0 0 1.5 2.5 2.5 0.5 3 3 GP7 5.5 6.5 5.5 10 7 13 5.5 9.5 13 GP8 1 4.5 0.5 3 7.5 4.5 13.5 17.5 11.5 # Passed 8/8 8/8 8/8 7/8 8/8 8/8 7/8 8/8 8/8 Neg. 48 39 46.5 39 48 54 39.5 54 67.5 Control 1 Neg. 40.5 53 44 44.5 54 48.5 59.5 61.5 45.5 Control 2 Virus Control Values: 93, 53, 56, 92, 67, 44 Virus Control Average Plaques: 67.5 Virus Control 50% Reduction: 33.8

EXPERIMENTAL SERIAL 507(Demonstrating Superior Efficacy of North American Equine E159(NAEE159) Vaccines, and that other North American Dominant Vaccines, such as North American Donkey E159(NADE159 will provide superior efficacy to NY99 vaccines)

Guinea Pig Serological Evaluation for West Nile Virus

TABLE 27 Experimental Serial 507 West Nile Guinea Pig Plaque Reduction Neutralization Results using WNV NY 1999 Isolate as Indicator Virus Number of Plaques/Sera Dilution Guinea Pig Number 4 8 16 32 64 GP1 >10 >15 >15 >14.5 >10.5 GP2 4.5 5 7.5 9.5 13 GP3 1 3.5 3.5 6 6.5 GP4 8 11.5 >13.5 >14.5 >14.5 GP5 6 7.5 7.5 8.5 9 GP6 8.5 9.5 9.5 12 14 GP7 7 8.5 9 >10.5 >14.5 GP8 5 10.5 10.5 14 14 GP9 5.5 7 7.5 10 10 GP10 5.5 6.5 8.5 >12.5 14 # Passed 9/10 6/10 5/10 2/10 1/10 Neg. Control 1 ≧13.5 ≧13.5 ≧13 ≧13 ≧14.5 Neg. Control 2 ≧15.5 ≧14.5 ≧16 ≧17 ≧16.5 Virus Control Values: ≧24, ≧15, ≧14, ≧16, ≧18, ≧20 Virus Control Average Plaques: ≧17.8 Virus Control 50% Reduction: ≧8.9

TABLE 28 Experimental Serial 507 West Nile Guinea Pig Plaque Reduction Neutralization Results Using North American Equine E159(NAEE159)as Indicator Virus Number of Plaques/Sera Dilution Guinea Pig Number 2 4 8 16 32 64 GP1 17 14 18.5 14.5 19.5 26 GP2 2.5 3.5 2 6 17 15 GP3 5.5 10 4.5 9 5 11.5 GP4 11.5 10 15 15.5 19 19.5 GP5 13 23 23.5 19.5 32.5 13 GP6 5.5 8.5 12 11 13 14 GP7 8.5 12 14 15 16 12 GP8 14.5 14 18 19.5 25.5 27.5 GP9 1.5 3 3 8.5 15.5 7 GP10 12.5 12 7 18.5 14 13 # Passed 9/10 9/10 7/10 7/10 5/10 7/10 Neg. Control 1 24.5 21 22 23.5 22 25 Neg. Control 2 24 33 29 29 24.5 34.5 Virus Control Values: 40, 38, 34, 35, 28, 23 Virus Control Average: 33 Virus Control 50% Reduction: 16.5 Discussion and Conclusions

Guinea pigs were vaccinated and sera tested for West Nile Virus antibody. This assay established that a titer of 1:12 in vaccinated guinea pigs correlates to protection in a horse vaccination/challenge study that provides at least one year duration of immunity for WNV vaccine prepared using a North American Dominant isolate of WNV, such as North American Equine E159(NAEE159).

Concurrently with guinea pig vaccinations, WNV vaccine prepared using a North American Dominant isolate of WNV, North American Equine E159(NAEE159), was also administered to horses (20 vaccinates and 10 controls) via primary immunization followed by booster immunization 3 weeks later. More than one year post-booster vaccination, horses were subjected to virulent West Nile Virus challenge, and were protected when compared to non-vaccinated controls. Vaccinated horses were protected from viremia, clinical signs, mortality, and encephalitic lesions after virulent heterologous challenge with West Nile Virus.

In addition the data substantiate the superior efficacy of WNV vaccines prepared using North American Dominant WNV, as opposed to previously developed vaccines derived from WNV NY99. The sera from the vaccinated guinea pigs were tested for neutralizing antibody to both a North American Dominant isolate of WNV and to WNV isolate NY99. Titers to the isolate frequently occurring in North America, namely North American Dominant (NAEE159), were consistently higher in vaccinated guinea pigs as compared to titers to the isolate that is no longer reported to be present in nor causing disease in North America, WNV NY99. Hence, the vaccine displayed superior activity in stimulating neutralizing antibodies to North American Dominant WNV, as opposed to NY99 WNV. These data support the conclusion of the superior efficacy of WNV vaccines prepared from North American Dominant WNV isolates as contrasted with earlier less effective vaccines prepared from or based on the NY99 WNV isolate.

Example 10

This Example illustrates the genetic differences between North American WNV strains and North American Dominant WNV strains, as used in the present invention.

Materials and Methods

Relevant areas of the genome of WNV NY99 and the North American Dominant WNV isolates suitable for preparation of a novel, superior vaccine were sequenced and compared to confirm the key genetic differences. Examples of North American Dominant isolates used in vaccine preparation include North American Equine E159(NAEE159) (ATCC Accession No. PTA-9409) and North American Donkey E159(NADE159).

Results and Conclusions

The critical Envelope (E) protein and Non-Structural 5 (NS5) protein was sequenced in these WNV isolates using standard laboratory techniques to determine genetic differences in nucleotide sequence as contrasted with WNV NY99. Notably, the North American Dominant isolates, of which specific examples are North American Equine E159(NAEE159) and North American Donkey E159(NADE159), displayed the changes which characterize North American Dominant WNV isolates and distinguish them from NY99 WNV, namely, the U to C mutation and C to U mutation at positions 1442 and 2466, respectively, of the nucleotide sequence encoding the E protein and the C to U mutation at position 9352 in the sequence encoding the NS5 protein. FIGS. 10-17 show the sequence alignments of various regions of isolates. The alignments in the E region are relative to publically available reference sequences for a NY 99 isolate (deposited in GenBank as AY590210) and a North American Dominant isolate (WN 02 isolate) deposited in GenBank as AY590223. The alignments in the NS5 region are also relative to publically available reference sequences for a NY 99 isolate (deposited in GenBank as AY369442) and a North American Dominant isolate (WN 02 isolate) deposited in GenBank as AY369440). As shown by these alignments, North American Dominant WNV isolates have the same sequence changes relative to the NY 99 isolate as those defined in the definition for a North American Dominant WNV isolate. These sequences are provided herein as SEQ ID NOS. 1-22, the full length genome of a WN99 isolate is provided as SEQ ID NO. 23, and the protein encoded by the full length genome of SEQ ID NO. 23 is provided as SEQ ID NO. 24. 

The invention claimed is:
 1. An immunogenic composition comprising a killed or inactivated West Nile Virus or any antigen thereof, wherein said West Nile Virus isolate comprises Horse Origin 2005, deposited with the ATCC under accession number PTA-9409.
 2. The immunogenic composition according to claim 1, wherein said strain is present in an amount from about 10^(2.0) TCID₅₀/mL-10^(10.0) TCID₅₀/mL per dose.
 3. The immunogenic composition according to claim 1, wherein said immunogenic composition further comprises suitable excipients or pharmaceutical carrier.
 4. The immunogenic composition according to claim 3, wherein said suitable excipients or pharmaceutical carrier is/are selected from the group consisting of a diluent, adjuvant, antimicrobial agent, inactivating agent, and combinations thereof.
 5. The immunogenic composition according to claim 4, wherein said adjuvant is selected from the group consisting of, a polymer of acrylic or methacrylic acid, non-metabolized oil, and combinations thereof.
 6. The immunogenic composition according claim 1, wherein said immunogenic composition is administered in one or more doses.
 7. The immunogenic composition according to claim 1, wherein one dose of said immunogenic composition is formulated in 0.5 ml to 2.5 ml.
 8. The immunogenic composition according to claim 1, wherein said immunogenic composition is safe for use in foals or horses 4 months of age or older.
 9. The immunogenic composition according to claim 1, wherein said immunogenic composition further comprises at least one antigenic component of one or more additional viruses selected from the group consisting of Eastern Equine Encephalomyelitis Virus, Western Equine Encephalomyelitis Virus and Venezuelan Equine Encephalomyelitis Virus, Tetanus Toxoid, and combinations thereof.
 10. The immunogenic composition according to claim 9, wherein said immunogenic composition comprises at least one antigenic component of Equine Herpes Virus.
 11. The immunogenic composition according to claim 10, wherein said Equine Herpes Virus is selected from the group consisting of the strains deposited with the ATCC under accession Nos. PTA-9525 or PTA-9526, and combinations thereof.
 12. The immunogenic composition according to claim 9, wherein said immunogenic composition comprises at least one antigenic component of Equine Influenza Virus.
 13. The immunogenic composition according to claim 12, wherein said Equine Influenza Virus is selected from the group consisting of Influenza/Equine-2/Ohio/03, Influenza/Equine-2/KY/95, Influenza/Equine-2/New Market/2/93, and combinations thereof.
 14. The immunogenic composition according to claim 12, wherein said Equine Influenza Virus is selected from the group consisting of the strains deposited with the ATCC under accession Nos. PTA-9522, PTA-9523 or PTA-9524 and combinations thereof.
 15. The immunogenic composition according to claim 9, wherein said Western Equine Encephalomyelitis Virus is the strain deposited with the ATCC under accession number PTA-9410.
 16. The immunogenic composition according to claim 9, wherein said Eastern Equine Encephalomyelitis Virus is the strain deposited with the ATCC under accession number PTA-9412.
 17. A method for reducing the incidence or lessening the severity of clinical symptoms associated with or caused by West Nile Virus in an equine or a herd of equines comprising the step of administering the immunogenic composition according to claim 1 to an animal in need thereof.
 18. The method according to claim 17, wherein said immunogenic composition provides duration of immunity of at least 12 months after the administration of one dose. 